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

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

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 2 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 3 Report

A well 1km deep is filled with a liquid of density $950\text{kg/m}^3$ and $g = 10\text{m/s}^2$, the pressure at the bottom of the well is

9.6 × 10

^{6}

N/m

^{2}

9.5 x 10

^{5}

N/m

^{2}

9.4 x 10

^{6}

N/m

^{2}

9.5 x 10

^{6}

N/m

^{2}

Answer Details

P = Pa + ρgh = (1.00 × 10

^{5}

) + (950 × 10 × 1000)
P = 10

^{5}

+ (95 × 10

^{5}

) = 10

^{5}

(1 + 95) = 96 × 10

^{5}

P = 9.6 × 10

^{6}

N/m

^{2}

Read lesson note on Pressure (JAMB)

Read lesson note on Motion (WAEC)

Pressure

Motion

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Question 4 Report

Which of the following is consistent with Charles' law?

I

II

III

IV.

I

II

III

IV

Answer Details

This is the correct graph. The graph is volume against 1/ temperature where temperature is in Celsius.

Read lesson note on Gas Laws (JAMB)

Read lesson note on Temperature And Its Measurement (JAMB)

Gas Laws

Temperature And Its Measurement

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Question 5 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 6 Report

If a body moves with a constant speed and at the same time undergoes an acceleration, its motion is said to be

oscillation

circular

rotational

rectilinear

Answer Details

If a body moves with a constant speed but at the same time undergoes an acceleration, its motion is called rectilinear motion. This means that the body moves in a straight line and its speed changes at a constant rate, causing an acceleration. It is different from oscillation, circular and rotational motions which involve changes in direction, as well as changes in speed.

Read lesson note on Rectilinear Acceleration (WAEC)

Rectilinear Acceleration

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Question 7 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 8 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 9 Report

A body moves in SHM between two point 20m on the straight line Joining the points. If the angular speed of the body is 5 rad/s. Calculate its speed when it is 6m from the center of the motion.

20 m/s

30 m/s

40 m/s

50 m/s

Answer Details

From two parts 20m apart
a = 10m, x = 6m, A = 5
V = ω

\sqrt{A^{2} - X^{2}}

= 5

\sqrt{10^{2} - 6^{2}}

= 40m/s

Read lesson note on Simple Harmonic Motion (WAEC)

Simple Harmonic Motion

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Question 10 Report

A car moving at 20m/s with its horn blowing (f = 1200Hz) is chasing another car going at 15m/s. What is the apparent frequency of the horn as heard by the driver being chased?

1.22KHz

2.40KHz

8.12KHz

1.22Hz

Answer Details

f

_{1}

=

f(v - v

_{o}

)v - v

_{s}

=

1200(340 - 15)340 - 20

=

1.22KHz

Read lesson note on Position, Distance And Displacement (WAEC)

Position, Distance And Displacement

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Question 11 Report

A cone is in unstable equilibrium has its potential energy

decreased

increased

unchanged

oscillating

Answer Details

In unstable equilibrium, potential energy decreases as the height decreases.

Read lesson note on Newton’s Laws Of Motion (WAEC)

Read lesson note on Equilibrium Of Forces (WAEC)

Newton’s Laws Of Motion

Equilibrium Of Forces

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Question 12 Report

The following are some units

I. Ns

II. Non

III. $ \mathrm{Nm}^{-2} $

IV. $ \mathrm{J^\circ K}^{-1} $

V. $ \mathrm{JKj}^{-1} $

What are the units of latent heat?

I

II

III

V

Answer Details

Latent heat or specific latent heat = L

Heat

energy

=

mL

or

L

=

Hm

=

energymass

Read lesson note on Work, Energy & Power (JAMB)

Read lesson note on Measurements And Units (JAMB)

Work, Energy & Power

Measurements And Units

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Question 13 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.

Read lesson note on Newton’s Laws Of Motion (WAEC)

Newton’s Laws Of Motion

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Question 14 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 15 Report

A ray of light passes through the centre of curvature of a concave mirror and strikes the mirror. At what angle is the ray reflected?

180

^{o}

90

^{o}

0

^{o}

60

^{o}

Answer Details

When a light ray passes through the center of curvature of a concave mirror and strikes the mirror, the reflected ray will be reflected back on itself, creating an angle of 0 degrees. Therefore, the correct answer is 0o.

View Answer

Question 16 Report

Radio waves belongs to the class of ware whose velocity is about

340m/s

3 × 10

^{6}

m/s

3 × 10

^{8}

m/s

3 × 10

^{- 8}

m/s

Answer Details

Radio waves belong to the class of waves whose velocity is approximately 3 x 10^8 m/s. This velocity is commonly denoted as the speed of light, which is the speed at which all electromagnetic waves, including radio waves, travel in a vacuum. This constant velocity is one of the fundamental principles of physics and is important in understanding the behavior and properties of light and other electromagnetic waves. The speed of light is incredibly fast, and it's difficult for us to imagine just how fast it is. To put it into perspective, light can travel around the Earth's equator almost 7.5 times in just one second. This high speed is essential for radio communication, as it enables radio waves to travel long distances in a short amount of time, allowing us to communicate with people and devices far away from us.

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 17 Report

One newton × One meter equals?

One water

One Joule

One ampere

One kilogram

Answer Details

One newton times one meter is equal to one Joule. A newton is the unit of measurement for force, and a meter is the unit of measurement for distance. When force is applied over a distance, work is done, which is measured in Joules. Therefore, one newton multiplied by one meter results in one Joule of work done. The other options listed (one water, one ampere, one kilogram) are not correct units of measurement for this calculation.

Read lesson note on Scalars And Vectors (JAMB)

Scalars And Vectors

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Question 18 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 19 Report

The lower fixed part of a faulty thermometer reads 2°C while the upper fixed point is 100°C.

What is the true temperature when the thermometer reads 51°C?

52°C

50°C

49°C

46°C

Answer Details

Since the thermometer is faulty, it is not measuring the temperature accurately. To find the true temperature, we need to determine the extent of the error in the thermometer. We can do this by comparing the difference between the lower fixed point and the reading with the difference between the upper fixed point and the true temperature. Since the lower fixed point reads 2°C and the upper fixed point reads 100°C, and the thermometer reading is 51°C, we can calculate the error as follows: True temperature = (51°C - 2°C) / (51°C - 2°C) * (100°C - 51°C) + 51°C = 50°C So, the true temperature when the thermometer reads 51°C is 50°C, which is option B.

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 20 Report

The height at which the atmosphere cases to exist is about 80km. If the atmospheric pressure on the ground level is 760mmHg, the pressure at a height of 20km above the ground level is

$(\rho_m = 13.6g/cm^3\ \rho = 0.00013g/cm^3)$

380mmHg

570mmHg

190mmHg

480mmHg

Answer Details

ρ $_{m}$ h $_{m}$ = ρ $_{a}$ h $_{a}$
13.68(760 - p) × 10 $^{- 3}$ = 13 × 10 $^{- 5}$ (20 × 10 $^{3}$ )

760

-

p

=

13 × 10

^{- 5}

× 20 × 10

^{3}

13.68 × 10

^{- 3}

=

19.00

×

10

^{1}

760 - p = 190
p = 760 - 190 = 570mmHg

Read lesson note on Pressure (JAMB)

Pressure

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Question 21 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.

View Answer

Question 22 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 23 Report

The resultant capacitance in the figure above is

0.4μf

0.8μf

1.8μf

4.5μf

Answer Details

For the parallel arrangement = 2 + 4 = 6μf

For

the

series

arrangement

=

1C

_{T}

=

12

+

13

+

16

+

14

1C

_{T}

=

1512

C

_{T}

=

1215

=

0.8μf

Read lesson note on Capacitors (JAMB)

Capacitors

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Question 24 Report

The volume of 0.354g of helium at 273°C and 114cm of mercury pressure is 2667cm$^{3}$. Calculate the volume

2000.25 cm

^{3}

200.025 cm

^{3}

4003.27 cm

^{3}

2010.25 cm

^{3}

Answer Details

m = 0.354g, T $_{1}$ = 273°C = 273 + 273 = 576K
P $_{1}$ = 114cmHg, V $_{1}$ = 2667cm $^{3}$ at STP
T $^{2}$ = 273K, P $_{2}$ = 76cmHg, V $_{2}$ = ?

P

^{1}

V

^{1}

T

^{1}

=

P

^{2}

V

^{2}

T

^{1}

V

_{2}

=

114 × 2667 × 27376 × 576

=

2000.25cm

^{3}

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 25 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 26 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 27 Report

The part of the human eye that does similar work as the diaphragm of a camera lens is the

Ciliary muscles

Pupil

Iris

Retina

Answer Details

The part of the human eye that does similar work as the diaphragm of a camera lens is the iris. The iris is the colored part of the eye and is responsible for controlling the amount of light that enters the eye. Just like the diaphragm in a camera lens, the iris can adjust its size to allow more or less light into the eye. This helps to regulate the amount of light reaching the retina, which is responsible for sensing light and transmitting the image to the brain.

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

Structure Of The Atom (Nigeria Only)

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Question 28 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 29 Report

When two objects A and B are supplied with the same quantity of heat, the temperature change in A is obtained to be twice that of B. The mass of P is half that of Q. The ratio of the specific heat capacity of A to B is

1 : 4

4 : 1

1 : 1

2 : 1

Answer Details

θA = 2θ $_{B}$ ,

m

_{A}

=

12

m

_{B}

H = MCθ
m $_{A}$ c $_{A}$ θ $_{A}$ = m $_{B}$ c $_{B}$ θ $_{B}$
( 1/2 m $_{B}$ )C $_{A}$ (2θ $_{B}$ ) = m $_{B}$ c $_{B}$ θ $_{B}$

C

_{A}

C

_{B}

=

11

⇒ 1 : 1

Read lesson note on Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Question 30 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 31 Report

A vibrator causes water ripples to travel across the surface of a tank. The wave travels 50cm in 2s and the distance between successive crests is 5cm. Calculate the frequency of the vibrator

5Hz

6Hz

5.2Hz

25Hz

Answer Details

The frequency of the vibrator can be calculated using the formula: frequency = speed / wavelength where speed is the speed of the wave, and wavelength is the distance between successive crests. In this case, we are given that the wave travels 50cm in 2s, which means the speed of the wave is: speed = distance / time = 50cm / 2s = 25cm/s We are also given that the distance between successive crests is 5cm, which is the wavelength. Therefore, the frequency of the vibrator is: frequency = speed / wavelength = 25cm/s / 5cm = 5Hz So the correct answer is 5Hz.

Read lesson note on Motion (WAEC)

Motion

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Question 32 Report

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 kinetic energy of the body

an increase in the potential energy of the body

an increase in the height of the body

Answer Details

The condition for stable equilibrium of a body that has been slightly displaced from its equilibrium position is "an increase in the potential energy of the body." When an object is at its equilibrium position, it has a minimum potential energy. When the object is displaced from its equilibrium position, it has a higher potential energy. For the object to be in stable equilibrium, it must be able to return to its equilibrium position after it has been displaced. If the potential energy of the object increases as it is displaced, it means that the equilibrium position is a point of stable equilibrium. This is because the object will experience a restoring force that will push it back towards its equilibrium position, as the potential energy decreases. Therefore, an increase in potential energy is a condition for a body to be in stable equilibrium after it has been slightly displaced from its equilibrium position. An increase in kinetic energy or height does not necessarily indicate stability, as it depends on the specific situation and other factors at play.

Read lesson note on Newton’s Laws Of Motion (WAEC)

Read lesson note on Scalars And Vectors (JAMB)

Read lesson note on Equilibrium Of Forces (WAEC)

Newton’s Laws Of Motion

Scalars And Vectors

Equilibrium Of Forces

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Question 33 Report

The mass of water vapour in a given volume of air is 0.05g at 20°C, while the mass of water vapour required to saturate it at the same temperature is 0.15g. Calculate the relative humidity of the air.

3.33%

5.55%

33.33%

55.55%

Answer Details

Relative humidity is a measure of how much water vapor the air is holding compared to the maximum amount it could hold at a given temperature. It is expressed as a percentage. To calculate the relative humidity of the air in this problem, we need to use the formula: Relative humidity = (mass of water vapor in air / mass of water vapor required for saturation) x 100% We are given that the mass of water vapor in the air is 0.05g and the mass of water vapor required for saturation at the same temperature is 0.15g. Plugging these values into the formula, we get: Relative humidity = (0.05 / 0.15) x 100% = 33.33% Therefore, the relative humidity of the air is 33.33%. So the answer is 33.33%.

Read lesson note on Quantity Of Heat (JAMB)

Quantity Of Heat

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Question 34 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 35 Report

In a slide wire bridge, the balance is obtained at a point 25cm from one end of wire 1m long. The resistance to be tested is connected to that end and a standard resistance of $3.6\,\Omega$ is connected to the other end of the wire. Determine the value of the unknown resistance

3.2

Ω

1.4

Ω

3.21

Ω

1.2

Ω

Answer Details

$\frac{R}{3.6} = \frac{75}{25} = \frac{1}{3}$

3R = 3.6

R = 1.2 $Ω$

View Answer

Question 36 Report

The limiting frictional force between two surfaces depends on

I. the normal reaction between the surfaces

II. the area of surface in contact

III. the relative velocity between the surfaces

IV. the nature of the surfaces

I only

II only

III only

I and IV only

Answer Details

- Friction depends on the nature of the surfaces in contact
- Solid friction is independent of the area of the surfaces in contact and the relative velocity between the surfaces.

Read lesson note on Friction (JAMB)

Friction

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Question 37 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

Read lesson note on Gravitational Field (WAEC)

Gravitational Field

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Question 38 Report

- angle of dip is zero at the magnetic equator
- angle of variation is the same as angle of declination.

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

- angle of dip is zero at the magnetic equator
- angle of variation is the same as angle of declination.

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

Read lesson note on Electric Field (WAEC)

Magnetic Field (Part 2)

Electric Field

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Question 39 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 40 Report

Which of the following statement about the electromagnet shown above is correct?

when the current flows from A to B, the end A will be in north pole

when the current flows from A to B, the end A will be south pole

when the current flows from A to B, the end B will be north pole

none of the above

Answer Details

A - B = S - N.
Also, starting end of the current is south while terminating end is North.

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Electric Field

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