Which of the following does NOT describe the Image formed by a plane minor?

Same distance from mirror as object

Temperature is the property of a body which is proportional to the ____.

average kinetic energy of its molecules

total kinetic energy of its molecules

average kinetic energy of its molecules

Which of the following is true of an electrical charge?

Positive charge means deficit electrons

Negative charge means excess of electrons

electric current means movement of electrons

The time rate of loss of heat by a body is proportional to the

difference in temperature between the body and its surroundings

temperature of its surroundings

difference in temperature between the body and its surroundings

ratio of the temperature of the body to that of its surroundings

Electrical appliances in homes are normally earthed so that

a person touching the appliances is safe from electric shock

both the a.c. and d.c. sources can be used

the appliances are maintained at a higher pd than the earth

the appliances are maintained at a lower pd than the earth

Natural radioactivity consists of the emission of

α- particles, β - rays and g-rays

Which of the following best describes the energy changes which take place when a steam engine drives a generator which lights a lamp?

heat ----> Kinetic ----> Electricity ----> Heat and Light

heat ----> Light----> Sound ----> Kinetic

Kinetic ----> Light ----> Heat ----> Electricity

heat ----> Kinetic ----> Electricity ----> Heat and Light

electricity ----> Kinetic ----> Heat ----> Light

High-energy electromagnetic waves

JAMB UTME - Physics - 2018 | Green Bridge CBT

Question 1 Report

What is the resultant resistance of the circuit in the image shown?

8Ω

11Ω

4Ω

3.6Ω

Answer Details

Formulae resistance in parallel
= 1/R = 1/R1 +1/R2
1/R = 1/2 +1/2 = 1
Resistance are now in series
R = 1 + 3 + 4
= 8 ohms

Read lesson note on Capacitors (JAMB)

Capacitors

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Question 2 Report

Which of the following diagrams represents correctly an n-p-n transistor?

i.

ii

iii

i

ii

iii

View Answer

Question 3 Report

The resistance of a 40W car head lamp, drawing current from a 12V battery is ____.

0.3Ω

3.3Ω

3.6Ω

4.8Ω

Answer Details

The resistance of a 40W car headlamp can be calculated using Ohm's Law, which states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points, and inversely proportional to the resistance (R) of the conductor. The equation can be written as V = IR. Since the power (P) of the headlamp is given as 40W and the voltage is 12V, we can calculate the current using the equation P = IV. Substituting I = P/V, we get I = 40/12 = 3.33A. Finally, using Ohm's Law, we can calculate the resistance as R = V/I = 12/3.33 = 3.6Ω. So, the resistance of the 40W car headlamp, drawing current from a 12V battery, is 3.6Ω.

Read lesson note on Current Electricity (JAMB)

Current Electricity

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Question 4 Report

The critical angle for light travelling from a transparent medium to air s measured as 340. The refractive index of the medium is

0.56

1.50

1.79

2.02

Answer Details

The critical angle is the angle of incidence at which light is just able to pass through the interface between two media and not reflect back. When light travels from a medium with a higher refractive index to a medium with a lower refractive index, it slows down and bends towards the normal. If the angle of incidence is increased, the light will eventually reach a point where it will not be able to escape the higher index medium and will be totally reflected back. This is the critical angle. The formula for the critical angle can be expressed as follows: sin(θc) = n2/n1 Where θc is the critical angle, n1 is the refractive index of the first medium, and n2 is the refractive index of the second medium. In this case, the first medium is the transparent medium and the second medium is air, which has a refractive index of approximately 1. By substituting the value of sin(θc) with the value of 340, and n2 with 1, we can solve for n1. sin(340) = n1/1 n1 = 1/sin(340) The value of n1 calculated using this formula is approximately 1.79, which means that the refractive index of the transparent medium is 1.79.

Read lesson note on Refraction Of Light Through Plane And Curved Surfaces (JAMB)

Refraction Of Light Through Plane And Curved Surfaces

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Question 5 Report

The tendency of a body to remain at rest when a force is applied to it is called.

Impulse

Momentum

Inertia

Friction

Answer Details

The tendency of a body to remain at rest or to continue moving with a constant velocity (in a straight line at a constant speed) when no force is acting on it is called inertia. Inertia is a property of matter, and the amount of inertia depends on the mass of an object. Inertia can also be thought of as a resistance to changes in motion, meaning that an object at rest will tend to stay at rest, and an object in motion will tend to stay in motion unless acted upon by an external force. This property of inertia is what makes it difficult to start, stop, or change the direction of motion of an object. The force required to overcome the inertia of an object depends on the mass of the object and the magnitude of the acceleration desired. Therefore, the greater the mass of an object, the greater its inertia, and the more force required to change its motion.

Read lesson note on Scalars And Vectors (WAEC)

Read lesson note on Equilibrium Of Forces (WAEC)

Scalars And Vectors

Equilibrium Of Forces

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Question 6 Report

Which of the following phenomena is the practical evidence for the existence of the continual motion of molecules.

Transitional Motion

Rotational Motion

Brownian Motion

Oscillatory Motion

Answer Details

Brownian motion is the practical evidence for the existence of the continual motion of molecules. This phenomenon is observed as the random movement of particles suspended in a fluid, such as a liquid or a gas, due to the constant bombardment of the fluid molecules. It was first described by the Scottish botanist Robert Brown in 1827 and provides strong evidence for the kinetic theory of matter, which states that all matter is made up of constantly moving particles. The random movement of the suspended particles can be observed through a microscope and is a direct result of the continual motion of the fluid molecules.

Read lesson note on Thermal Expansion (JAMB)

Read lesson note on Structure Of Matter And Kinetic Theory (JAMB)

Thermal Expansion

Structure Of Matter And Kinetic Theory

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Question 7 Report

In homes, electrical appliances and lamps are connected in parallel because

less current will be used

less voltage will be used

parallel connection does not heat up the wires

series connection uses high voltage

Electrostatics

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Question 8 Report

A lens of focal length 15cm forms on erect image which is three times the size of the object. The distance between the object and the image is ___.

10cm

20cm

30cm

40cm

Answer Details

We can use the lens formula, 1/f = 1/v - 1/u, where f is the focal length of the lens, v is the distance between the lens and the image, and u is the distance between the lens and the object. From the problem, we know that the focal length of the lens is 15 cm, and the image is erect and three times the size of the object. This means that the image distance v is positive and the object distance u is negative (since the object is in front of the lens). Let's assume that the object distance u is -x cm, where x is a positive number. Then, the image distance v is +3x cm, since the image is three times the size of the object. Substituting these values into the lens formula, we get: 1/15 = 1/(+3x) - 1/(-x) Simplifying the right-hand side, we get: 1/15 = (1 + 3)/3x Multiplying both sides by 3x, we get: 3x/15 = 4 Simplifying, we get: x = 20 Therefore, the distance between the object and the lens is -20 cm (since it is in front of the lens), and the distance between the image and the lens is +60 cm (since it is behind the lens). The distance between the object and the image is the sum of these distances, which is: (-20) + (+60) = 40 cm Therefore, the answer is 40cm.

Read lesson note on Optical Instruments (JAMB)

Optical Instruments

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Question 9 Report

Which of the following phenomena cannot be explained by the molecular theory of matter?

Conduction

Convection

Expansion

Radiation

Answer Details

Conduction: the flow of internal energy from a region of higher temperature to lower temperature
Convection: heat transfer due to bulk movement of molecules within fluids
Expansion: the action of becoming larger or more extensive

Read lesson note on Thermal Expansion (JAMB)

Thermal Expansion

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Question 10 Report

A positively charged rod X is brought near an uncharged metal sphere Y and is then touched by a finger with X still in place. When the finger is removed, the result is that Y has

no charge and a zero potential

a positive charge and a zero potential

a negative charge and a positive potential

a negative charge and a negative potential

Electrostatics

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Question 11 Report

The photo cell works on the principle of the

Voltaic cell

Emission of electron by incident radiation

Emission of protons by incident radiation

Photographic plate

Answer Details

The photocell works on the principle of the emission of electrons by incident radiation. In simple terms, a photocell is a device that converts light energy into electrical energy. It does this by using a material (such as silicon) that releases electrons when it is exposed to light. These electrons can then be collected and used to produce a current, which can be used to power an electrical device. The more light that hits the photocell, the more electrons are released and the greater the electrical current.

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 12 Report

If the fraction of the atoms of a radioactive material left after 120years is \( \frac{1}{64} \), what is the half-life of the material? \( \frac{1}{64} \)

20 years

10 years

2 years

24 years

Answer Details

The half-life of a radioactive material is the time it takes for half of the atoms in a sample to decay. The fraction of atoms left after a certain number of half-lives can be calculated using the formula: fraction left = (1/2)^(number of half-lives) Let's use this formula to solve the problem. We know that the fraction of atoms left after 120 years is 1/64, which means that: (1/2)^(number of half-lives) = 1/64 To solve for the number of half-lives, we can take the logarithm of both sides: log[(1/2)^(number of half-lives)] = log(1/64) Using the rule that log(a^b) = b*log(a), we can simplify the left side of the equation: number of half-lives * log(1/2) = log(1/64) Dividing both sides by log(1/2), we get: number of half-lives = log(1/64) / log(1/2) Using a calculator or the change of base formula, we can evaluate this expression: number of half-lives = 6 Therefore, the half-life of the material is 120/6 = 20 years.

Read lesson note on Work, Energy And Power (WAEC)

Work, Energy And Power

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Question 13 Report

The differences observed in solids, liquids and gases may be accounted for by

their relative masses

their melting points

the spacing and forces acting between the molecules

the different molecules in each of them

Answer Details

The differences observed in solids, liquids, and gases can be accounted for by the spacing and forces acting between the molecules. In a solid, the molecules are packed closely together, so they have a fixed shape and volume. The intermolecular forces are strong enough to keep the molecules in a fixed position relative to one another. In a liquid, the molecules are still close together, but they are free to move around each other. The intermolecular forces are weaker than in a solid, so the molecules can slide past one another, giving the liquid its ability to flow and take the shape of its container. In a gas, the molecules are widely spaced and are in constant motion. The intermolecular forces are very weak, so the molecules are free to move around and fill any available space. Gases have no fixed shape or volume. So, the differences observed in solids, liquids, and gases can be explained by the spacing and forces acting between the molecules. It's not about their relative masses, melting points, or the different molecules in each of them.

Read lesson note on Thermal Expansion (JAMB)

Read lesson note on Structure Of Matter And Kinetic Theory (JAMB)

Thermal Expansion

Structure Of Matter And Kinetic Theory

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Question 14 Report

When an atom loses or gain a charge it becomes

An electron

An ion

A neutron

A proton

Answer Details

When an atom loses or gains a charge, it becomes an ion. An ion is a type of atom that has an unequal number of protons and electrons, giving it a net electrical charge. If an atom loses one or more electrons, it becomes positively charged and is called a cation. On the other hand, if an atom gains one or more electrons, it becomes negatively charged and is called an anion. So, in summary, an atom can lose or gain electrons to become an ion, which has a net electrical charge.

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Electrostatics

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Question 15 Report

In the diagram shown, If the south-poles of two magnets stroke a steel bar, the polarities at T and V will respectively be

north and south

south and south

north and north

south and north

Magnets And Magnetic Fields

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Question 16 Report

Palm oil from a bottle flows out more easily after it has been heated because the

Molecules are given energy during the heating

Friction between oil layers is reduced

Oil molecules force each other out

Adhesion between the oil molecules and those of the bottle is increased

Answer Details

Molecules cannot be given energy during the heating and the molecules of oil cannot force each other out

Read lesson note on Thermal Expansion (JAMB)

Read lesson note on Structure Of Matter And Kinetic Theory (JAMB)

Thermal Expansion

Structure Of Matter And Kinetic Theory

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Question 17 Report

To keep a vehicle moving at a constant speed V requires power P from the engine. The force provided by the engine is

P

V

(

\frac{1}{2}

)V

PV

P

V²

Answer Details

The force provided by the engine to keep a vehicle moving at a constant speed is proportional to the power (P) required from the engine. This power is proportional to the product of the speed (V) and force (P), so the relationship can be expressed as P = kV, where k is a proportionality constant.

Read lesson note on Work, Energy And Power (WAEC)

Work, Energy And Power

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Question 18 Report

A room is heated by means of a charcoal fire, an occupants of the room standing away from the fire is warmed mainly by

Convection

Radiation

Conduction

Reflection

Answer Details

The main way that the occupants of a room standing away from a charcoal fire are warmed is by radiation. Radiation is the transfer of heat energy through electromagnetic waves, and it can travel through empty space. In this scenario, the charcoal fire emits radiation in the form of infrared waves, which travel through the air and warm up the objects (including the occupants) in the room. Convection, on the other hand, is the transfer of heat through the movement of fluids (such as air), but in this case, the air in the room is not being actively circulated by a fan or other mechanism. Conduction involves the transfer of heat through direct contact between two objects, but the occupants are not in direct contact with the fire. Reflection refers to the bouncing of radiation off a surface, but it is not a significant factor in this scenario as most of the radiation is absorbed by the objects in the room.

Read lesson note on Heat Transfer (JAMB)

Read lesson note on Gravitational Field (WAEC)

Read lesson note on Conduction Of Electricity Through (JAMB)

Heat Transfer

Gravitational Field

Conduction Of Electricity Through

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Question 19 Report

A car traveled at a uniform speed of 100km/h, spends 15m moving from point A to point B along its route. The distance between A and B is

50km

25km

15km

10km

Answer Details

To calculate the distance between point A and point B, we can use the formula: Distance = Speed x Time where the speed is given as 100 km/h and the time is given as 15 minutes, which we need to convert to hours. 1 hour = 60 minutes, so 15 minutes = 15/60 hours = 0.25 hours. Now, we can substitute these values into the formula: Distance = 100 km/h x 0.25 h = 25 km Therefore, the distance between point A and point B is 25 km. is the correct answer.

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Question 20 Report

An object moves in a circular path of radius 0.5m with a speed of \(1ms^{-1}\). What is its angular velocity?

8rads

^{- 1}

4rads

^{- 1}

1rads

^{- 1}

2rads

^{- 1}

Answer Details

Angular velocity is a measure of how fast an object is rotating around a center point. It's usually measured in radians per second (rad/s). To calculate angular velocity, we use the formula: angular velocity = linear velocity / radius. In this case, the linear velocity is 1 m/s, and the radius is 0.5 m. So, the angular velocity would be: 1 m/s / 0.5 m = 2 rad/s Therefore, the answer is 2 rad/s or 2rads^-1

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Read lesson note on Speed And Velocity (WAEC)

Motion

Speed And Velocity

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Question 21 Report

A narrow beam of white light can be split up into different colours by a glass prism. The correct explanation is that

white light Is an electromagnetic wave

the prism has all the colours of the white light

different colours of white light travel with different speeds in glass

white light has undergone total Internal reflection in the prism

Answer Details

The correct explanation for why a narrow beam of white light can be split up into different colors by a glass prism is that different colors of white light travel with different speeds in glass. White light is made up of different colors with different wavelengths, ranging from violet to red. When a narrow beam of white light passes through a glass prism, the different colors refract at slightly different angles due to the fact that their wavelengths are different. This causes the different colors to spread out and form a spectrum. The amount of refraction that occurs depends on the speed of light in the medium. Different colors of light have different speeds in glass due to the fact that their wavelengths are different. This means that they will refract at different angles as they pass through the glass prism, causing them to spread out. So, the correct explanation for why a narrow beam of white light can be split up into different colors by a glass prism is that different colors of white light travel with different speeds in glass. Therefore, is the correct explanation. is incorrect because it describes what white light is made up of, but does not explain how it is split up into colors by a prism. is incorrect because a prism does not have all the colors of white light, but rather it separates the colors that are already present in white light. is incorrect because total internal reflection occurs when light is completely reflected back into the same medium, which is not what happens when white light is split up by a prism.

Read lesson note on Electromagnetic Waves: Types Of Radiation In Electromagnetic Spectrum (WAEC)

Electromagnetic Waves: Types Of Radiation In Electromagnetic Spectrum

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Question 22 Report

In the diagram shown, which of the simple pendulum will resonate with P when set into oscillation?

U

T

R and T

Q and R

Equilibrium Of Forces

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Question 23 Report

Musical instruments playing the same note can be distinguished from one another owing to the difference in their

quality

pitch

intensity

loudness

Answer Details

Different musical instruments playing the same note can be distinguished from one another due to the difference in their "timbre" or "tone color." Timbre refers to the unique character or quality of a sound that allows us to distinguish it from other sounds even when they have the same pitch and loudness. For example, a piano and a guitar playing the same note will sound different due to the differences in their timbre. This is why we can tell the difference between different instruments and why some instruments are better suited to certain styles of music than others.

View Answer

Question 24 Report

Which of the following concepts is not an evidence of the particles nature of matter?

Diffusion

Brownian motion

Diffraction

Crystallization

Answer Details

The particle nature of matter refers to the idea that matter is made up of tiny particles that are constantly moving. Diffusion, Brownian motion, and crystallization are all examples of phenomena that can be explained by the particle nature of matter. However, diffraction is not an evidence of the particle nature of matter. Diffraction is a phenomenon that occurs when waves encounter an obstacle or a slit, causing them to spread out and interfere with each other. While particles can also exhibit diffraction, this is a property of waves and is not specific to particles. In summary, diffusion, Brownian motion, and crystallization are all evidences of the particle nature of matter, but diffraction is not.

Read lesson note on Thermal Expansion (JAMB)

Thermal Expansion

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Question 25 Report

The density of 400cm3 of palm oil was 0.9gcm-3 before frying. If the density of the oil was 0.6gcm-3 after frying, assuming no loss of oil due to spilling, its new volume was?

1360cm

^{3}

600cm

^{3}

240cm

^{3}

8000m

^{3}

Answer Details

The density of a substance is defined as its mass per unit volume. Therefore, the mass of the palm oil before frying was: Mass = Density x Volume = 0.9 g/cm³ x 400 cm³ = 360 g After frying, the mass of the palm oil remains the same, but its density changes to 0.6 g/cm³. Therefore, the new volume of the palm oil can be calculated by rearranging the density formula: Volume = Mass / Density = 360 g / 0.6 g/cm³ = 600 cm³ So the new volume of the palm oil after frying is 600 cm³. is the correct answer.

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Question 26 Report

Which of the following instruments is most suitable for measuring the outside diameter of a narrow pipe in a few millimeters in diameter?

Pair of calipers

Meter rule

Micrometer screw gauge

Tape rule

Answer Details

The most suitable instrument for measuring the outside diameter of a narrow pipe in a few millimeters in diameter is a micrometer screw gauge. A micrometer screw gauge is a precision measuring instrument that can accurately measure small dimensions with high accuracy. It has a spindle that moves towards an anvil and a scale that indicates the measurement. The spindle moves in response to a small rotation of the thimble, allowing for precise and sensitive measurements. In contrast, a pair of calipers or a meter rule may not be accurate enough for measuring such small dimensions, and a tape rule may not be able to fit inside the narrow pipe. Therefore, a micrometer screw gauge is the most suitable option for measuring the outside diameter of a narrow pipe in a few millimeters in diameter.

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Measurements And Units

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Question 27 Report

A man hears his echo from a nearby hill 2s after he shouted. If the frequency of his voice is 260Hz and the wavelength is 1.29m, how far away is the hill

330.0m

335.4m

660.0m

670.8m

Answer Details

The speed of sound in air is approximately 343 meters per second at room temperature. The formula for the speed of sound is:

Speed of sound = Frequency × Wavelength

In this problem, we are given the frequency (260 Hz) and the wavelength (1.29 m) of the sound wave. We can use these values to calculate the speed of sound:

Speed of sound = 260 Hz × 1.29 m = 335.4 m/s

Next, we need to use the fact that the man hears his echo 2 seconds after he shouted. Since the sound wave traveled from the man to the hill and then back to the man, the total distance traveled by the sound wave is twice the distance from the man to the hill. We can use the formula:

Distance = Speed × Time

to calculate the distance from the man to the hill:

Distance = (335.4 m/s) × (2 s/2) = 335.4 m

Therefore, the hill is 335.4 meters away from the man. The answer is option (B), 335.4m.

Read lesson note on Production And Propagation Of Waves (WAEC)

Read lesson note on Sound Waves (WAEC)

Production And Propagation Of Waves

Sound Waves

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Question 28 Report

The amount of heat needed to raise the temperature of 10kg of Copper by 1K is its

specific heat capacity

latent heat

heat capacity

internal energy

Answer Details

The correct answer is "specific heat capacity." Specific heat capacity is a measure of how much heat energy is required to raise the temperature of a certain amount of a substance by 1 degree Celsius (or 1 Kelvin, which is the same size as 1 degree Celsius). In this case, we are dealing with 10kg of copper, so we need to know the specific heat capacity of copper. The specific heat capacity of copper is 0.385 J/g°C (joules per gram per degree Celsius). To calculate the amount of heat needed to raise the temperature of 10kg of copper by 1K, we need to know the total mass of copper (10kg) and the specific heat capacity of copper (0.385 J/g°C). The formula for calculating the amount of heat energy required is: Heat energy = mass x specific heat capacity x change in temperature Since we want to raise the temperature by 1K, the change in temperature is 1K. So, the amount of heat energy required to raise the temperature of 10kg of copper by 1K is: Heat energy = 10kg x 0.385 J/g°C x 1K = 3.85 kJ Therefore, it takes 3.85 kilojoules (kJ) of heat energy to raise the temperature of 10kg of copper by 1K.

Read lesson note on Quantity Of Heat (JAMB)

Read lesson note on Temperature And Its Measurement (JAMB)

Quantity Of Heat

Temperature And Its Measurement

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Question 29 Report

Convex mirrors are used as driving mirrors because images formed are

erect, Virtual and diminished

erect, real and diminished

erect, virtual and magnified

inverted, virtual and diminished

Answer Details

Convex mirrors are used as driving mirrors because the images formed by them are "erect, virtual, and diminished." Let me explain what these terms mean: - Erect: It means that the image appears upright, just like the actual object. This is important for a driving mirror because it allows the driver to perceive the correct orientation of the vehicles behind them. - Virtual: It means that the image appears to be behind the mirror, and not in front of it. This is also important for a driving mirror because it allows the driver to see a wider field of view without having to turn their head. - Diminished: It means that the image is smaller than the actual object. This is important for a driving mirror because it allows the driver to see a larger area behind them while still fitting it within the mirror's frame. Overall, these properties make convex mirrors ideal for use as driving mirrors as they provide the driver with an accurate view of the vehicles behind them without sacrificing their field of view.

Read lesson note on Simple A.C. Circuits (WAEC)

Simple A.C. Circuits

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Question 30 Report

A resistor connected to a 12V battery draws a current of 2A. The energy dispatched in the resistor in 5 minutes is ___.

3,600J

6,000J

7,200J

14,400J

Answer Details

To calculate the energy dispatched in the resistor, we need to use the formula: Energy = Power x Time Where Power is the amount of electrical power consumed by the resistor, and is equal to the product of the voltage across the resistor and the current flowing through it: Power = Voltage x Current In this case, the voltage across the resistor is 12V, and the current flowing through it is 2A. Therefore, the power consumed by the resistor is: Power = 12V x 2A = 24W Now, we can substitute this value of power along with the given time of 5 minutes into the formula for energy: Energy = 24W x 5min x 60s/min = 7,200J Therefore, the energy dispatched in the resistor in 5 minutes is 7,200J. is the correct answer.

Read lesson note on Electrical Energy And Power (JAMB)

Electrical Energy And Power

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Question 31 Report

Mercury which is spilled onto a glass surface forms ball-like shapes because____.

Mercury is a metal

The cohesive force between its molecules is greater than the adhesive force between mercury and glass molecules

The cohesive force between its molecules is less than the adhesive force between mercury and glass molecules

The viscosity of mercury is height

Answer Details

In case of small drops of mercury, the gravitational potential energy is negligible in comparison to the potential energy due to surface tension.Consequently, to keep the drop in equilibrium, the mercury drop’s surface tends to contract so that its surface area will be the least for a sphere and the drops will be spherical.
But in the case of bigger drops of mercury, the potential energy due to gravity is predominant over the potential energy due to surface tension.Consequently, to keep equilibrium , the mercury drop tends to assume minimum potential energy as possible, the drop becomes oval in shape and lower center of gravity.

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Liquids At Rest

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Question 32 Report

Which of the following may be used to explain a mirage?

I. Layers of air near the road surface have varying refractive indices in hot weather

II. Road surfaces sometimes become good reflectors in hot weather

III. Light from the sky can be reflected upwards after coming close to the road surface.

I and III only

II and III only

II only

I, II and III

Answer Details

The phenomenon of a mirage can be explained by options I and III. A mirage is an optical illusion that occurs when light rays passing through a medium with varying refractive indices create a false image of distant objects or even the sky. In hot weather, the air near the road surface becomes hotter and less dense than the air above, causing the light passing through it to bend and create a reflection of the sky or objects in the distance. This effect is known as a temperature inversion. Additionally, light from the sky can be reflected upwards after coming close to the road surface, adding to the illusion of a reflected object or the sky. Option II, which suggests that road surfaces become good reflectors in hot weather, is not a valid explanation for a mirage. Therefore, the correct answer is: I and III only.

Read lesson note on Reflection Of Light At Plane And Curved Surfaces (JAMB)

Reflection Of Light At Plane And Curved Surfaces

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Question 33 Report

A particle of mass M initially at rest splits into two. If one of the particles of mass M1 moves with velocity V1 , the second particle moves with velocity

M1V1

M-M1

M1V1

M1-M

M1V1

M

MV

M-M1

Answer Details

When a particle of mass M splits into two, the total mass is conserved, and so the sum of the masses of the two resulting particles must be equal to M. If one of the particles of mass M1 moves with velocity V1, we can use the law of conservation of momentum to determine the velocity of the second particle. The law of conservation of momentum states that the total momentum of a system of particles remains constant if no external forces act on the system. In this case, the initial momentum of the system is zero, since the particle was initially at rest. After the particle splits, the momentum of the system is the sum of the momenta of the two resulting particles. Let's use the subscript 1 to represent the first particle of mass M1 and the subscript 2 to represent the second particle of mass M-M1. By conservation of momentum, we have: 0 = M1*V1 + (M - M1)*V2 Solving for V2, we get: V2 = -M1/M*(V1) Therefore, the second particle moves in the opposite direction with velocity -M1/M*(V1). This means that the two particles move in opposite directions, with the ratio of their velocities determined by the ratio of their masses. Option (D) in the table shows the correct answer, which is -M1/M*(V1).

Read lesson note on Scalars And Vectors (JAMB)

Scalars And Vectors

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Question 34 Report

In the diagram given if the atmospheric pressure is 760mm, the pressure in the chamber G Is

660mm

890mm

690mm

860mm

Pressure

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Question 35 Report

A 20kg mass is to be pulled up a slope inclined at 300 to the horizontal. If efficiency of the plane is 75%. The force required to pull the load up the plane is J [g=10ms\(^{-2}\)]

87N

73.5N

133.3N

533.2N

Answer Details

The force required to pull a 20kg mass up a slope inclined at 300 can be calculated using the formula: force = mass * gravity * sin(angle) where mass is 20kg, gravity is 10 m/s^2 and angle is 300. The formula for efficiency is: efficiency = output force / input force where output force is the force required to pull the mass up the slope and input force is the force applied to the rope. Since the efficiency of the plane is 75%, the input force is 4 times the output force. So, the output force can be calculated as: output force = input force / 4 input force = mass * gravity * sin(angle) / efficiency input force = 20 * 10 * sin(300) / 0.75 input force = 533.2 N And the output force can be calculated as: output force = input force / 4 output force = 533.2 / 4 output force = 133.3 N So, the force required to pull the load up the plane is 133.3 N.

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Gravitational Field

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Question 36 Report

The process by which protons are converted into helium atoms with a tremendous release of energy is called?

thermionic emission

nuclear fission

thermonuclear fusion

photoelectric emission

Answer Details

The process by which protons are converted into helium atoms with a tremendous release of energy is called "thermonuclear fusion". In this process, two light atomic nuclei combine to form a heavier nucleus, releasing a huge amount of energy in the form of light and heat. This is the same process that powers the sun and other stars. The high temperatures and pressures required for fusion to occur can only be achieved in stars or in controlled environments such as fusion reactors. Thermonuclear fusion is different from nuclear fission, which is the process of splitting a heavy nucleus into lighter nuclei with the release of energy. Thermionic emission and photoelectric emission are different processes that involve the emission of electrons from a material due to heating or exposure to light, respectively.

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Structure Of The Atom (Nigeria Only)

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Question 37 Report

Water of mass 150g at \(60^\circ\)c is added to 300g of water at \(20^\circ\)c and the mixture is well stirred. Calculate the temperature of the mixture.(neglect heat losses to the surroundings)

33

^{o}

c

40

^{o}

c

25

^{o}

c

10

^{o}

c

Answer Details

To solve this problem, we can use the principle of conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted from one form to another. In this case, the energy transferred is in the form of heat. We can use the formula: Q = m*c*(ΔT) where Q is the heat transferred, m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature. First, we can calculate the heat transferred from the hot water to the cold water: Q1 = 150g * 4.18 J/(g°C) * (60°C - T) Q1 = 627 * (60 - T) where T is the temperature of the mixture. Next, we can calculate the heat transferred from the cold water to reach the final temperature of the mixture: Q2 = 300g * 4.18 J/(g°C) * (T - 20°C) Q2 = 1254 * (T - 20) Since the heat transferred between the two water samples must be equal, we can set Q1 equal to Q2 and solve for T: 627 * (60 - T) = 1254 * (T - 20) 37620 - 627T = 1254T - 25080 1881T = 62760 T = 33.4°C Therefore, the temperature of the mixture is approximately 33°C. Answer: 33°C

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Temperature And Its Measurement

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Question 38 Report

Electrical power is transmitted at a high voltage rather than a low voltage because the amount of energy loss is due to

Heat dissipation

Production of eddy currents

Excessive current discharge

Excessive voltage discharge

Answer Details

The primary reason that power is transmitted at high voltages is to increase efficiency. As electricity is transmitted over long distances, there are inherent energy losses along the way. High voltage transmission minimizes the amount of power lost as electricity flows from one location to the next. How? The higher the voltage, the lower the current. The lower the current, the lower the resistance losses in the conductors. And when resistance losses are low, energy losses are low also. Electrical engineers consider factors such as the power being transmitted and the distance required for transmission when determining the optimal transmission voltage

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Question 39 Report

Which of the following is an essential physical property of the wires uses for making fuses ?

Low density

Hypothermal conductivity

Low electrical resistivity

Low melting point

Answer Details

The essential physical property of the wire used for making fuses is low melting point. This means that the wire should have a low temperature at which it melts and breaks, interrupting the flow of electrical current. This is important in a fuse because when there is an overload of electrical current, the wire will melt, breaking the circuit and preventing damage to the electrical system. The other options, low density, low electrical resistivity, and hypothermal conductivity, are not as important for a fuse wire. Low density is the property of a material to be light, and it doesn't necessarily affect the performance of a fuse wire. Low electrical resistivity is the property of a material to have low resistance to the flow of electrical current, and it doesn't necessarily affect the performance of a fuse wire either. Hypothermal conductivity is the property of a material to conduct heat poorly, and it also doesn't necessarily affect the performance of a fuse wire.

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Gravitational Field

Electrostatics

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Question 40 Report

The product of force and time is?

Impulse

Momentum

Inertia

Friction

Answer Details

The product of force and time is known as impulse. Impulse can be defined as the change in momentum that an object experiences as a result of a force being applied to it over a period of time. In simpler terms, impulse is the "push" that an object receives from a force acting on it for a certain amount of time. The more force applied, or the longer the time the force is applied, the greater the impulse and the greater the change in momentum of the object. It's important to note that impulse is a vector quantity, meaning it has both magnitude and direction. Impulse is a measure of the ability of a force to cause an object to change its velocity, and can be used to explain many phenomena in physics, such as why a heavy object is harder to stop than a lighter one, or why a soccer ball changes direction when it is kicked.

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Work, Energy And Power

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