The momentum of a car moving at a constant speed in a circular track

can be zero depending on its position in the track

can be both positive and negative

can be zero depending on its position in the track

Ripple in a power supply unit is caused by

using an alternating current source

The mass of a nucleus is the

total number of its proton and neutrons

total number of its protons and electrons

A body was slightly displaced from its equilibrium position. Which one of the following is a condition for its stable equilibrium

an increase in the potential energy of the body

an increase in the kinetic energy of the body

an increase in the potential energy of the body

an increase in the height of the body

Which of these is observed when air is pumped out of a discharge tube without lowering its pressure

the conductivity of the air increases

the conductivity of the air decreases

Gases conduct electricity under

normal pressure and low voltage

An alternating current can induce voltage because it has

weaker magnetic field than direct current

JAMB UTME - Physics - 2019 | Green Bridge CBT

Question 1 Report

If the time of flight is 96seconds, calculate the horizontal range through the point of projection.

84400m

69000m

61440m

24000m

Answer Details

Time of flight, T = 96s
R = (Ucosθ) *time* T = 640 × 96 = 61,440m

Read lesson note on Motion (JAMB)

Motion

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Question 2 Report

The volume of a stone having an irregular shape can be determined using?

meter rule

measuring cylinder

vernier calliper

micrometer screw gauge

Answer Details

The volume of a stone with an irregular shape can be determined using a measuring cylinder. A measuring cylinder is a glass or plastic container with a narrow cylindrical shape and markings on the side to indicate the volume it contains. To determine the volume of an irregularly shaped stone, you would fill the measuring cylinder with water, carefully lower the stone into the water, and note the increase in the volume of the water. The difference in the volume of the water before and after the stone was added is equal to the volume of the stone. The meter rule, vernier calliper, and micrometer screw gauge are all measuring instruments, but they are not designed to measure the volume of irregularly shaped objects. The meter rule is a measuring tool used for measuring length. The vernier calliper is used for measuring the diameter of objects, and the micrometer screw gauge is used for precise measurements of small distances.

Read lesson note on Measurements And Units (JAMB)

Measurements And Units

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Question 3 Report

A single force which produces the same effect as a set of forces acting together at a point is known as the

component

equilibrant

resultant

resistant

Answer Details

The single force which produces the same effect as a set of forces acting together at a point is known as the "resultant". In other words, the resultant is the net force that results from combining all the individual forces acting on an object. It represents the combined effect of all the forces acting on the object and is the force that would produce the same motion as the original set of forces acting together. Therefore, when solving problems in physics, it is often useful to find the resultant force in order to determine the overall effect of multiple forces on an object.

Read lesson note on Scalars And Vectors (WAEC)

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

Read lesson note on Equilibrium Of Forces (WAEC)

Scalars And Vectors

Simple A.C Circuits

Equilibrium Of Forces

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Question 4 Report

In the molecular explanation, heat is transferred by the

free electron

free atoms

free molecules

free solids

Answer Details

- Conduction is explained in terms of the free electrons
- Convection is explained in terms of the movement of the fluid involved
- Radiation is explained in terms of invisible electromagnetic waves.

Read lesson note on Thermal Expansion (JAMB)

Thermal Expansion

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Question 5 Report

The pin-hole camera produces a less sharply defined image when the

pin-hole is larger

illumination is less

screen is further from the pin-hole

object is further from the pin-hole

Answer Details

The pin-hole camera produces a less sharply defined image when the pin-hole is larger. A pin-hole camera works by allowing light to pass through a small hole (the pin-hole) and project an inverted image of the outside world onto a screen or surface located behind the hole. The smaller the pin-hole, the sharper the resulting image, as light passing through a smaller hole produces less diffraction or spreading out of the light. When the pin-hole is larger, more light enters the camera, but the light rays also become more scattered, resulting in a less well-defined image. This is because the larger opening allows more light rays to enter at different angles, creating a wider range of paths that the light can take as it travels through the camera and onto the screen. As a result, the image is less clear and less defined, with less sharp edges and more blurring. is the correct answer because it correctly identifies the effect of a larger pin-hole on the image produced by the pin-hole camera. less illumination, would actually produce a dimmer image, but it would not affect the sharpness or definition of the image. the distance of the screen from the pin-hole, and the distance of the object from the pin-hole, would affect the size of the image and the scale of the objects, but they would not affect the sharpness or definition of the image.

Read lesson note on Light Energy (JAMB)

Read lesson note on Structure Of The Nucleus (WAEC)

Light Energy

Structure Of The Nucleus

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Question 6 Report

In which of the points labelled A, B, C, D and E on the conductor shown would electric charge tend to concentrate most

A

B

C

E

Answer Details

- Charge are mostly concentrated at the outermost part of a hollow conductor
- Charge are also mostly concentrated at the pointed ends or places with high density point.

Read lesson note on Electric Field (WAEC)

Read lesson note on Electrostatics (JAMB)

Electric Field

Electrostatics

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Question 7 Report

A siren having a ring of 200 hole makes 132 rev/min. A jet of air is directed on the set of holes. Calculate the frequency and wavelength in air of the note produced (take v = 350m/s)

0.875m

0.625m

0.335m

0.125m

Answer Details

n = 200, S = 132 rev/min, v = 350m/s $^{2}$

f

=

ns

=

200

×

132

revmin

×

1min60s

=

440Hz

λ

=

vf

=

350440

=

0.875m

Read lesson note on Quantity Of Heat (JAMB)

Quantity Of Heat

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Question 8 Report

The lead-acid accumulator consists of

lead as the positive electrode

lead acid as the negative electrode

hydrochloric acid as the electrolyte

tetraoxosulphate (vi) acid as the electrolyte

Answer Details

- the positive pole is lead peroxide (PbO

_{2}

)
- the negative pole is head
- the electrolyte is H

_{2}

SO

_{4}

Read lesson note on Electric Cells (JAMB)

Electric Cells

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Question 9 Report

The angular dispersion of a prism depends on

The index of refraction only

The angle of incidence as well as the index of refraction

The angle of incidence only

The thickness of the prism only

Answer Details

Dispersion is due to different refractive indices speeds and wavelengths.

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

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

Reflection Of Light At Plane And Curved Surfaces

Refraction Of Light Through Plane And Curved Surfaces

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Question 10 Report

Calculate the velocity ratio of a screw jack of pitch 0.2cm if the length of the tommy bar is 23cm

230

π

23

π

70

π

140

π

Answer Details

P = 0.2cm, L = r = 23cm

VR

=

2?rP

=

2?LP

=

2?×230.2

=

230?

Read lesson note on Simple Machines (JAMB)

Simple Machines

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Question 11 Report

When a girl moves towards a plane mirror at a speed of 4.0m/s, the distance between the girl and her image reduces a speed of

2 m/s

4 m/s

8 m/s

12 m/s

Answer Details

v

=

dt

or

v

α

d

d = x, v = 4m/s
d = 2x, v = ? (girl and image)

v

=

2 × 4x

=

8

ms

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 12 Report

The following are parts of the eye

I. Retina

II. Pupil

III. Iris

The correct equivalent in the camera in the same order are

Diaphragm, Aperture, film

Aperture, Diaphragm, Film

Film, Diaphragm, Aperture

Film, Aperture, Diaphragm

Answer Details

- retina is similar to film
- pupil is similar to aperture
- iris is similar to diaphragm

Read lesson note on Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

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Question 13 Report

A supply of 400V is connected across capacitors of 3μf and 6μf in series. Calculate the charge

8 x 10

^{- 4}

C

4 x 10

^{- 2}

C

8 x 10

^{- 3}

C

4 x 10

^{- 8}

C

Answer Details

C

_{T}

=

C

_{1}

× C

_{2}

C

_{1}

+ C

_{2}

=	3 × 63 + 6

= $\frac{18}{9}$ = 2μf
Q = CV
⇒ 2 × 10 $^{- 6}$ × 400
⇒ 800 × 10 $^{- 6}$ C = 8 × 10 $^{- 4}$ C

Read lesson note on Capacitors (JAMB)

Capacitors

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Question 14 Report

The statement 'Heat lost by the hot body equals that gained by the cold one' is assumed when determining specific that heat capacity by the method of mixtures. Which of the following validates the assumption?

I. Lagging the Calorimeter

II. Ensuring that only S.I units are used

III. Weighing the calorimeter, the lid and the stirrer.

I only

I and II only

I and III only

II and III only

Answer Details

The assumption 'Heat lost by the hot body equals that gained by the cold one' is based on the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred from one system to another. Thus, to validate this assumption, it's important to have a well-designed and insulated calorimeter so that as little heat as possible is lost to the environment. This is accomplished by lagging the calorimeter (Option I). Additionally, using the correct units (Option II) helps ensure that the energy transfer is accurately calculated and reported. Weighing the calorimeter, the lid, and the stirrer (Option III) is important for accurately measuring the amount of heat transferred, but by itself is not enough to validate the assumption. Therefore, the correct answer is "I and III only".

Read lesson note on Electric Cells (JAMB)

Read lesson note on Quantity Of Heat (JAMB)

Electric Cells

Quantity Of Heat

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Question 15 Report

The earth's gravitational field intensity at its surface is about

$G = 6.7 \times 10^{-11}\,\mathrm{Nm^2/kg^2}$, mass of the earth is $6 \times 10^{24}\,\mathrm{kg}$, radius of the earth is $6.4 \times 10^6\,\mathrm{m}$, g on the earth = $9.8\mathrm{m/s^2}$

6.7N/kg

7.9N/kg

8.0N/kg

9.8N/kg

Answer Details

The earth's gravitational field intensity at its surface can be calculated using the formula: g = G * M / r^2 where G is the gravitational constant, M is the mass of the earth, r is the radius of the earth, and g is the gravitational field intensity at the surface of the earth. Substituting the given values, we get: g = (6.7 × 10^-11 Nm^2/kg^2) * (6 × 10^24 kg) / (6.4 × 10^6 m)^2 g = 9.8 N/kg (approx.) Therefore, the answer is 9.8N/kg.

Read lesson note on Gravitational Field (JAMB)

Gravitational Field

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Question 16 Report

Water and Kerosine are drawn respectively into the two limbs of a Hare's apparatus. The destiny of water is $1.0\mathrm{g\,cm^{-3}}$ and the density of kerosine is $0.80\mathrm{g\,cm^{-3}}$. If the height of the water column is 20.0cm, calculate the height of the kerosine column.

1.6cm

16.0cm

20.0cm

25.0cm

Answer Details

Devices with different liquids
d $_{1}$ h $_{1}$ = d $_{2}$ h $_{2}$
1 × 20 = 0.8 × h

h

=

200.8

=

25cm

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 17 Report

The Earth's magnetic equator passes through Jos in Nigeria. At Jos, the

angle of variation is zero

magnetic declination is 90

angle of dip is zero

horizontal component at the Earth's field is zero

Answer Details

The Earth has a magnetic field that is generated by the movement of molten iron in its core. The magnetic field has different properties at different locations on the Earth's surface. The magnetic equator is an imaginary line on the Earth's surface where the inclination or tilt of the Earth's magnetic field is zero, meaning that the magnetic field lines are parallel to the Earth's surface. At Jos, Nigeria, the Earth's magnetic equator passes through, which means that the angle of inclination or dip of the Earth's magnetic field is zero. Therefore, the correct answer is that the angle of dip is zero. This means that a magnetic needle suspended by a thread or placed on a horizontal surface would remain horizontal and not point downwards or upwards, as it would at other locations on the Earth's surface. This makes Jos an important location for studying the Earth's magnetic field and for conducting experiments related to magnetism.

Read lesson note on Electromagnetic Field (Part 2) (WAEC)

Electromagnetic Field (Part 2)

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Question 18 Report

Which of the following statements are correct of the production and propagation of waves?

I. vibration produces waves

II. waves transmit energy along the medium

III. the medium through which the wave travels does not travel with the wave

IV. waves do not require any medium for transmission

I and IV only

II and IV only

III and IV only

I, II and III only

Answer Details

The correct statement is: I and II and III only. Explanation: - Statement I is correct because the production of waves involves some kind of disturbance that creates a vibration in the medium, which then propagates as a wave. - Statement II is correct because waves carry energy along the medium as they propagate. This is why waves can be used to transmit information or power over long distances. - Statement III is correct because the medium through which a wave travels does not move with the wave. Instead, the wave passes through the medium, causing it to oscillate or vibrate, but not to move along with the wave. - Statement IV is incorrect because most waves require a medium through which to propagate. For example, sound waves require air, water waves require water, and seismic waves require the Earth's crust. There are some types of waves, such as electromagnetic waves, that can propagate through a vacuum, but this is not true for all waves.

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

Production And Propagation Of Waves

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Question 19 Report

During the transformation of matter from the solid to the liquid state, the heat supplied does not produce a temperature increase because

the heat energy is quickly conducted away

the heat capacity has become very large as the substance melts

the heat gained is equal to the heat lost by the substance

all the heat is used to break the bonds holding the molecules of the solid together

Answer Details

During the transformation of matter from the solid to the liquid state, the heat supplied does not produce a temperature increase because all the heat is used to break the bonds holding the molecules of the solid together

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 20 Report

A safety precaution designed to prolong the life of a lead acid accumulator is

By topping up the cells with concentrated acid

The use of naked flame when charging the battery

Keeping the specific gravity of the electrolyte within specified range

By connecting wires to the terminals directly when testing the level of charging

Answer Details

- Topping is done with distilled water
- Naked flame should be avoided when charging the battery
- Direct connection of wires to the terminals should be avoided.

View Answer

Question 21 Report

According to kinetic molecular model, in gases

The molecules are very fast apart and occupy all the space made available.

The particles occur in clusters with molecules slightly farther apart.

The particles are closely packed together, they occupy minimum space and are usually arranged in a regular pattern.

The particles vibrate about fixed positions and are held together by the strong inter-molecular bond between them.

Answer Details

In kinetic molecular model, gases are energised and thus moves freely, fast as they occupy specific space

Read lesson note on Gas Laws (JAMB)

Read lesson note on Quantity Of Heat (JAMB)

Read lesson note on Thermal Expansion (JAMB)

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

Gas Laws

Quantity Of Heat

Thermal Expansion

Structure Of Matter And Kinetic Theory

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Question 22 Report

Which of the following equations is the correct definition of the reactance of an indicator L?

Reactance = (Amplitude of voltage)

\div

(Amplitude of current)

Reactance = (Amplitude of voltage) x (Amplitude of current)

Reactance = (Amplitude of current)

^{2}

\div

(Amplitude of voltage)

Reactance = (Amplitude of current)

^{2}

\div

(Amplitude of voltage)

\frac{1}{2}

Answer Details

The correct definition of the reactance of an inductor L is: Reactance = (Amplitude of voltage) ÷ (Amplitude of current) The reactance of an inductor is a measure of the opposition offered by the inductor to the flow of alternating current (AC). It is denoted by the symbol Xl and is measured in ohms. When AC flows through an inductor, a magnetic field is generated around the inductor, which opposes any changes in the current flowing through it. This opposition to the flow of current is called reactance. The reactance of an inductor depends on its inductance, frequency of the AC signal, and the amplitude of the AC signal. However, the reactance of an inductor is directly proportional to the frequency of the AC signal and the inductance of the inductor. The reactance of an inductor is also affected by the amplitude of the AC signal, but this effect is not as significant as the other two factors. is the correct definition of the reactance of an inductor, as it expresses the ratio of the amplitude of voltage to the amplitude of current, which is a common way to define reactance. is incorrect, as it represents the power delivered by the AC signal, not the reactance. and are also incorrect, as they involve squaring either the amplitude of current or the amplitude of voltage, which is not a valid method of calculating reactance. Therefore, the correct option is.

Read lesson note on Electric Field (WAEC)

Electric Field

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Question 23 Report

Three resistors with resistance 200Ω, 500Ω and 1kΩ are connected in series. A 6v battery is connected to either end of the combination. Calculate the potential difference between the ends of 200Ω resistance.

0.71V

0.7V

0.82V

0.8V

Answer Details

To calculate the potential difference between the ends of the 200Ω resistance, we need to use Ohm's Law, which states that the potential difference (V) across a resistor is equal to the current (I) flowing through the resistor multiplied by the resistance (R) of the resistor. First, we need to find the total resistance of the series combination of resistors. We add up the individual resistances: Total resistance = 200Ω + 500Ω + 1kΩ = 1.7kΩ Next, we can use Ohm's Law to find the current flowing through the circuit. We know that the battery voltage is 6V, and the total resistance is 1.7kΩ: I = V / R = 6V / 1.7kΩ = 0.0035A Now we can use Ohm's Law again to find the potential difference across the 200Ω resistor: V = IR = 0.0035A * 200Ω = 0.7V Therefore, the potential difference between the ends of the 200Ω resistance is 0.7V. The correct answer is option B.

Read lesson note on Current Electricity (JAMB)

Current Electricity

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Question 24 Report

If the attraction of the sun is suddenly ceased, the earth would continue to move in a straight line making a tangent with the original orbit. This statement is derived from Neutron's

First law of motion

Second law of motion

Third law of motion

Law of universal gravitation

Answer Details

The correct answer is the First law of motion. The First law of motion, also known as the law of inertia, states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. In this case, the earth is moving in its orbit around the sun because of the force of gravity between the two objects. If the force of gravity suddenly ceased, the earth would no longer be acted upon by an external force and would continue to move in a straight line, making a tangent with its original orbit. This idea is attributed to Sir Isaac Newton, who developed the laws of motion and the law of universal gravitation. However, the specific statement mentioned in the question is derived from the First law of motion.

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Newton’s Laws Of Motion

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Question 25 Report

When water is boiling, it

gets hotter

increase is mass

decreases in mass

changes to steam

Answer Details

When water is boiling, it changes from a liquid state to a gaseous state called steam. This happens when the water is heated to its boiling point, which is when it reaches a temperature of 100 degrees Celsius (212 degrees Fahrenheit) at sea level. As the water is heated, it absorbs energy and the molecules start to move faster and faster, eventually reaching a point where they escape into the air as steam. The temperature of the water during boiling does not change, as all the energy is being used to break the bonds between the water molecules rather than increasing the temperature. Therefore, the options "gets hotter," "increase in mass," and "decreases in mass" are not correct when describing what happens when water is boiling.

View Answer

Question 26 Report

The conductivity of gases at low pressure can be termed as

I. hot cathode emission

II. thermo ionic emission

III. cold cathode emission

IV. Field emission

I and II

II and III

III and IV

IV and V

Answer Details

As conduction of gases is at low pressure and high voltage, called field or cold cathode emission.

Read lesson note on Properties Of Waves: Reflection, Refraction, Diffraction (WAEC)

Properties Of Waves: Reflection, Refraction, Diffraction

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Question 27 Report

The point at which the molecules of a loaded wire begin to slide across each other resulting in a rapid increase in extension is

yield point

proportionality point

deformation point

elastic point

Answer Details

The point at which the molecules of a loaded wire begin to slide across each other resulting in a rapid increase in extension is called the yield point. At this point, the material no longer behaves elastically and becomes permanently deformed. The yield point is an important parameter in material science and engineering as it indicates the maximum stress a material can withstand before it begins to deform plastically. Therefore, the yield point is a critical factor to consider when designing materials for specific applications.

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Elasticity

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Question 28 Report

A microscope is focused on a mark on a table, when the mark is covered by a plate of glass 2m thick, the microscope has to be raised 0.67cm for the mark to be once more in focus. Calculate the refractive index.

1.52

1.68

2.58

1.82

Answer Details

R = th = 2cm, d = 0.67cm

n

=

RA

=

RR.d

=

22-0.67

=

1.52

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 29 Report

Which of the following is/are the limitations to the Rutherford's atomic models?

I. It is applicable when energy is radiated as electrons are revolving

II. It is applicable when energy is radiated in a continuous mode

III. It is applicable to an atom with only one electron in the other shell

I only

II only

I and II only

I, II and III only

Answer Details

Rutherford assumed that (I) energy is radiated when electrons are revolving (II) energy is radiated in a continuous mode. These are limitations of Rutherford's model

Read lesson note on Structure Of The Atom (Nigeria Only) (WAEC)

Structure Of The Atom (Nigeria Only)

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Question 30 Report

In semi-conductor, the carriers of current at room temperature are

electrons only

electrons and holes

holes only

electron and ions

Answer Details

In a semiconductor, the carriers of current at room temperature are both electrons and holes. Semiconductors are materials with properties that are in between those of conductors (e.g. metals) and insulators (e.g. rubber). At room temperature, a semiconductor crystal contains both free electrons and positively charged vacancies called holes. When a voltage is applied across the semiconductor, the electrons move towards the positive end of the circuit and the holes move towards the negative end. This movement of charge carriers constitutes an electric current. In summary, both electrons and holes can carry current in a semiconductor at room temperature, making the correct answer.

Read lesson note on Capacitors (JAMB)

Read lesson note on Electrostatics (JAMB)

Capacitors

Electrostatics

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Question 31 Report

Which of the following statements is/are correct for a freely falling body?

I. the total is entirely kinetic

II. the ratio of potential energy to kinetic energy is constant

III. the sum of potential and kinetic energy is constant

I only

II only

III only

I and III only

Answer Details

The correct answer is "III only". A freely falling body is one that is falling under the influence of gravity and experiences no other force or constraint. In this situation, the total energy of the body is conserved, meaning that the sum of its potential and kinetic energy remains constant. The potential energy of a body is directly proportional to its height above the ground, and its kinetic energy is directly proportional to its velocity. As the body falls, its potential energy decreases and its kinetic energy increases, but the total energy remains constant. Statement III is correct because the sum of potential and kinetic energy is indeed constant for a freely falling body. Statement I is incorrect because the body has both potential and kinetic energy, so the total energy is not entirely kinetic. Statement II is incorrect because the ratio of potential energy to kinetic energy is not constant for a freely falling body, as both are changing as the body falls.

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Work, Energy And Power

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Question 32 Report

Which of the following media allow the transmission of sound waves through them?

I. air

II. liquid

III. solids

I and II only

I and III only

II and III only

I, II and III

Answer Details

Sound waves are disturbances in a medium that propagate through the medium and transfer energy from one point to another. The transmission of sound waves depends on the physical properties of the medium, including its elasticity and density. Air (Option I) is a gas that is compressible and has a relatively low density, which makes it an excellent medium for transmitting sound waves. Liquids (Option II) are also able to transmit sound waves, although the speed of sound in liquids is slower than in gases because liquids are more dense and less compressible. Solids (Option III) are able to transmit sound waves as well, but their density and elasticity make them more rigid, which means that sound waves in solids tend to be transmitted as elastic waves or mechanical waves, rather than as acoustic waves. Therefore, the correct answer is "I, II, and III".

Read lesson note on Sound Waves (WAEC)

Sound Waves

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Question 33 Report

Any line or section taken through an advancing wave in which all the particles are in the same phase is called the

wavelength

wave coast

wave trough

wave front

Answer Details

The answer is: wave front. A wave front is any imaginary line or surface that connects all points of a wave that are in the same phase, meaning they are at the same point in their cycle. In other words, it is a line or surface that separates the points of a wave that are in-phase from those that are out-of-phase. For example, consider the ripples on the surface of a pond when a stone is thrown in. The wave fronts are the concentric circles that emanate from the point where the stone entered the water. All points along a given circle are in-phase, meaning the water molecules at those points are at the same point in their oscillation cycle. In summary, a wave front is a line or surface that separates points in a wave that are in-phase from those that are out-of-phase.

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

Production And Propagation Of Waves

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Question 34 Report

A rectangular solid black has length 10cm, breadth 5cm and height 2cm. If it lies on a horizontal surface, and has density $100\text{kg/m}^3$, calculate the pressure it exerts on the surface.

200 N/m

^{2}

100 N/m

^{2}

400 N/m

^{2}

Answer Details

To calculate the pressure that the rectangular solid exerts on the surface, we need to use the formula for pressure: Pressure = Force / Area In this case, the force is the weight of the rectangular solid, which we can calculate using the formula: Weight = Mass x Gravity The mass of the rectangular solid can be calculated using its density and volume: Mass = Density x Volume The volume of the rectangular solid is simply its length x breadth x height: Volume = Length x Breadth x Height = 10 cm x 5 cm x 2 cm = 100 cm3 We need to convert this volume to cubic meters to use the density given in kg/m3: Volume = 100 cm3 = 0.0001 m3 Now we can calculate the mass: Mass = Density x Volume = 100 kg/m3 x 0.0001 m3 = 0.01 kg The gravity is the acceleration due to gravity, which we can assume to be 9.81 m/s2. Therefore, the weight is: Weight = Mass x Gravity = 0.01 kg x 9.81 m/s2 = 0.0981 N Now we can use this weight to calculate the pressure on the surface. The surface area in contact with the rectangular solid is simply its length x breadth: Area = Length x Breadth = 10 cm x 5 cm = 50 cm2 We need to convert this area to square meters: Area = 50 cm2 = 0.005 m2 Therefore, the pressure is: Pressure = Force / Area = 0.0981 N / 0.005 m2 = 19.62 N/m2 We can convert this to units of N/cm2 or N/mm2 if desired. This is equivalent to: Pressure = 0.1962 N/cm2 = 0.0001962 N/mm2 So the pressure that the rectangular solid exerts on the surface is 19.62 N/m2, which is approximately 20 N/m2. Therefore, the answer is 200 N/m2.

Read lesson note on Pressure (JAMB)

Read lesson note on Measurements And Units (JAMB)

Pressure

Measurements And Units

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Question 35 Report

The distance between an object and its real image in a convex lens is 40cm. If the magnification of the image is 3, calculate the focal length of the lens

6.5 cm

7.5 cm

8.5 cm

4.5 cm

Answer Details

u + v = 40

$\frac{v}{u}$ = 3

v = 3u

u + 3u = 40

4u = 40

u = 10cm

v = 3u = 30cm

f = $\frac{u v}{u + v} = \frac{10 (30)}{10 + 30} = \frac{300}{40}$

= 7.5 cm

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Gravitational Field

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Question 36 Report

During the transformation of matter from the solid to the liquid state, the heat supplied does not produce temperature increase because

all the heat is used to break the bonds holding the molecules of the solid together

the heat capacity has become very large as the substance melts

the heat energy is quickly conducted away

the heat gained is equal to the heat lost by the substance

Answer Details

When a solid is heated to its melting point, the heat supplied is used to overcome the intermolecular forces holding the molecules in a fixed position, resulting in the breaking of these bonds. As a result, the solid transforms into a liquid without any change in temperature. This is because the heat energy supplied is used in breaking the bonds between molecules rather than increasing the kinetic energy of the molecules, which is what causes an increase in temperature. Therefore, the correct option is: "all the heat is used to break the bonds holding the molecules of the solid together."

Read lesson note on Change Of State (JAMB)

Change Of State

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Question 37 Report

Efficiency of conduction in liquids and gases compared to solids is

less efficient than solid

more efficient than solids

equally efficient to solids

efficiently may vary

Answer Details

The efficiency of conduction in liquids and gases compared to solids is generally less efficient. This means that solids are better conductors of heat and electricity than liquids and gases. This is because the particles in solids are closely packed and are tightly bound to one another, allowing heat and electricity to flow easily through the material. On the other hand, the particles in liquids and gases are more spread out and less tightly bound, making it more difficult for heat and electricity to flow through these materials. However, it is important to note that the efficiency of conduction can vary depending on the specific liquid or gas and the specific solid being compared. Some liquids and gases may have properties that make them better conductors than certain solids, but this is not a general rule.

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Question 38 Report

Aluminium is sometimes used as the leaf of an electroscope because it

is a light material

is a good conductor

is a good insulator

can be converted into thin sheets

Answer Details

- Aluminium can be made in thin sheet like Gold.
- the leaf is a thin material that can be diverged easily.

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 39 Report

In Sunlight, a blue flower looks blue because we see the flower by the light it

receives from our eyes

disperses

absorbed

reflect

Answer Details

In sunlight, a blue flower looks blue because it reflects blue light. When sunlight falls on an object, the object can either absorb, transmit, or reflect the light. The color of an object that we see is determined by the light that is reflected by that object. For example, if an object appears blue, it is because it reflects blue light and absorbs other colors. In the case of a blue flower in sunlight, the petals of the flower reflect blue light and absorb other colors. This reflected blue light enters our eyes, and our brain interprets it as the color blue. Therefore, we see the blue flower as blue because it reflects blue light, and that is the color that enters our eyes. In summary, the reason why a blue flower looks blue in sunlight is that it reflects blue light and absorbs other colors.

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

Read lesson note on Wave-particle Paradox (WAEC)

Read lesson note on Structure Of The Nucleus (WAEC)

Electromagnetic Waves: Types Of Radiation In Electromagnetic Spectrum

Wave-particle Paradox

Structure Of The Nucleus

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Question 40 Report

The pitch of a screw jack is 0.45cm and the arm is 60cm long. If the efficiency of the Jack is 75/π %, calculate the mechanical advantage.

400

300

200