# 2022 - JAMB Physics Past Questions & Answers - page 1

1

Which of the following is a derived unit?

A

Kilogram

B

Metre

C

Newton

D

Second

CORRECT OPTION: c

A derived unit is a unit of measurement in the International System of Units (SI) that is derived from one or more of the seven base units.

Examples of derived units:

• Velocity (m/s)
• Density kg/m3
• Force (Newton)
• Pressure (Pascal)
• Energy (Joule)
• Power (Watt)

We can derive other units from the independent units. The independent units are called Fundamental Units (or Base Units).

Examples of fundamental units are Mass in kilogram (kg); Electric Current, ampere (A); Temperature, kelvin (K); Amount of Substance, mole (Mol).

2

If a bar magnet is divided into two pieces, which of the following statement is correct?

A

two new magnets are created

B

the magnetic field of each separate piece becomes stronger

C

the electric field is created

D

the bar magnet is demagnetized

CORRECT OPTION: a

When a bar magnet is cut into two, the newly cut faces will become the new north or south poles of the smaller pieces. Hence, the two cut pieces will have their own north and south poles.

3

Consider the wave equation y = 5mm sin [1cm$$^{-1}$$x - 60s$$^{-1}$$t]. The wave number is?

A

0.1 cm$$^{-1}$$

B

10cm$$^{-1}$$

C

1.0cm$$^{-1}$$

D

2cm$$^{-1}$$

CORRECT OPTION: c

The angular wave number k is used to express the number of radians in a unit of distance.

Angular wave number is inversely proportional to the wavelength; hence the formula: k = 2π/λ.

4

An object 40 cm high is 30cm from the pinhole camera. If the height of the image formed is 20 cm. What is the distance of the image from the pin height?

A

15 cm

B

70 cm

C

40 cm

D

50 cm

CORRECT OPTION: a

M → $$\frac{Hi}{Ho}$$ = $$\frac{Di}{Do}$$

Where:
M = magnification
H = height of the image
Ho = height of the object
Do = distance from the object to the lens
Di = distance from the lens to the in-focus projected image

But Di = $$\frac{Hi * Do}{Ho}$$ → $$\frac{20 * 30}{40}$$
Image distance(Di) = 15cm

5

A bar magnet is placed near and lying along the axis of a solenoid connected to a galvanometer. The pointer of the galvanometer shows no deflection when?

A

the magnet is moved towards the stationary solenoid

B

there is no relative motion

C

the magnet is moved away from the stationary solenoid

D

the solenoid is moved away from the stationary magnet

CORRECT OPTION: b

No relative motion because when both the coil and the magnet are stationary there is no change in the magnetic flux hence, no current is induced in the coil.

6

Why do tyres have treads?

A

increase weight of tyres

B

increase friction

C

increase its longevity

D

look good

CORRECT OPTION: b

Regular tires have treads which provide your tires with the ability to grip the road thereby enhancing traction. The tread also helps the vehicle to accelerate or decelerate, as well as to brake reliably.

7

A car starts from rest and covers a distance of 40 m in 10 s. Calculate the magnitude of its acceleration.

A

3.20 ms$$^{-2}$$

B

0.25 ms$$^{-2}$$

C

0.80 ms$$^{-2}$$

D

4.00 ms$$^{-2}$$

CORRECT OPTION: c

S = ut + $$\frac{1}{2}$$at$$^2$$
40 = 0 x 10 + $$\frac{1}{2}$$a x 10$$^2$$
50a = 40
a = $$\frac{40}{50}$$
a = 0.8m/s$$^2$$

8

The relationship between the coefficient of linear expansion $$\alpha$$ and volumetric expansion ($$\gamma$$) is-----------------

A

$$\gamma$$ = $$\alpha ^{-3}$$

B

$$\gamma$$ = $$\alpha$$

C

3$$\alpha$$

D

$$\gamma$$ = $$\alpha ^{3}$$

CORRECT OPTION: c

volumetric expansion (γ) = 3 x linear expansion

9

Which of the following is not a consequence of hydrogen bubbles covering the copper plate of a primary cell?

A

formation of hydrogen bubbles on the electrode

B

increase in the resistance of the cell

C

local action

D

polarization

CORRECT OPTION: c

Local action defect caused by the impurities present in zinc rod.

10

A cell whose internal resistance is 0.55$$\Omega$$ delivers a current of 4 A to an external resistor. What is the lost voltage of the cell?

A

4.00 V

B

2.20 V

C

0.15 V

D

8.00 V

CORRECT OPTION: b

Lost voltage = I x R
= 4 x 0.55
= 2.2V

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