# Physics Past Questions

Physics is studied by science students and is concerned with the nature and properties of matter and energy. Physics topics include mechanics, heat, light and radiation, sound, electricity, magnetism, and the structure of atoms.

Study the following Physics past questions and answers for JAMB, WAEC, NECO and Post UTME. Prepare yourself with official past questions and answers for your upcoming examinations.

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Correct answers are highlighted in green.

### Question 1

Two magnets are used to magnetize a soft iron bar PQ as illustrated in the diagram given. The correct polarity at P and Q respectively

### Options

A) S and N

B) N and N

C) S and S

D) N and S

Exam Body: West African Examinations Council (WAEC)

### Question 2

In storing magnets, keepers are used to

### Options

A) reduced self-demagnetization

B) cancel the effect of the earth's magnetic field

C) protect the magnet from stray electric field

D) increase the strangth of the magnets

Exam Body: West African Examinations Council (WAEC)

### Explanation:

A magnet keeper, also known historically as an armature, is a paramagnetic bar made from soft iron or steel, which is placed across the poles of a permanent magnet to help preserve the strength of the magnet by completing the magnetic circuit.

### Question 3

A $10\mu \mathrm{C}$ charge moves with a velocity of $1.0 \times 10^5 ms^{-1}$ at right angle to a uniform magnetic field of flux density $5.0 \times 10^{-4}T.$ Calculate the force on the charge.

### Options

A) $5.0 \times 10^{-5} \mathrm{N}$

B) $5.0 \times 10^{-4} \mathrm{N}$

C) $5.0 \times 10^5 \mathrm{N}$

D) $5.0 \times 10^6 \mathrm{N}$

Exam Body: West African Examinations Council (WAEC)

### Explanation:

$F = qvB$
$= 10 \times 10^{-6} \times 1.0 \times 10^5 \times 10^{-4}$
$= 5.0 \times 10^{-4} \mathrm{N}$

### Question 4

Which of the following statements is not correct about steel and soft iron?

### Options

A) steel is more magnetized than soft iron

B) permanent magnets are usually made of steel

C) soft iron is more readily magnetized than steel

D) soft iron more readily loses its magnetism than steel

Exam Body: West African Examinations Council (WAEC)

### Question 5

What determines the polarity at the ends of an electromagnet? The

### Options

A) magnitude of the current passing through the wire

B) material of the core of the magnet

C) material of the coil

D) direction of current in the wire

Exam Body: West African Examinations Council (WAEC)

### Question 6

How many beta particle(s) are emitted in the radioactive decay of $^{198}_{79} \mathrm{Au} \leftarrow ^{198}_{80} \mathrm{Hg}$?

### Options

A) 1

B) 2

C) 3

D) 5

Exam Body: West African Examinations Council (WAEC)

### Explanation:

Because bata particles emit -1 and this is just balancing equation.

Explanation provided by Idowu Taye Ebenezer

### Question 7

The phenomenon by which two light atomic nuclear combine to form a heavy nuclide with the release of energy is known as

### Options

B) nuclear fusion

C) nuclear fission

D) chain reaction

Exam Body: West African Examinations Council (WAEC)

### Explanation:

Nuclear fusion is a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.

### Question 8

In a p-type semiconductor, the

### Options

A) number of holes are equal to the number of electrons

B) electrical resistivity increases

C) electrons are the majority charge carriers

D) holes are the majority charge carriers

Exam Body: West African Examinations Council (WAEC)

### Explanation:

In p-type semiconductors, holes are the majority carriers and electrons are the minority carriers. P-type semiconductors are created by doping an intrinsic semiconductor with acceptor impurities. A common p-type dopant for silicon is boron or gallium.

### Question 9

Let Δx be the uncertainty in the measurements of position and Δp the uncertainty in measurement of momentum. The uncertainty principle relation is given as

### Options

A) Δx . Δp = h

B) Δx . Δp ≤ h

C) Δx . Δp ≥h

D) Δx . Δp > h

Exam Body: West African Examinations Council (WAEC)

### Explanation:

Uncertainty principle, also called Heisenberg uncertainty principle or indeterminacy principle, statement, articulated (1927) by the German physicist Werner Heisenberg, that the position and the velocity of an object cannot both be measured exactly, at the same time, even in theory. The very concepts of exact position and exact velocity together, in fact, have no meaning in nature.

### Question 10

Two objects of masses 80kg and 50kg are separated by a distance of 0.2m. If the gravitational constant is 6.6 x 10-11Nm kg, calculate the gravitational attraction between them.

### Options

A) 4.9 × 10-9N

B) 1.3 × 10-6N

C) 6.6 × 10-8N

D) 6.6 × 10-6N

E) 2.6 × 10-9N

Exam Body: West African Examinations Council (WAEC)

### Explanation:

F = $\frac{Gm_1m_2}{r^2} = \frac{6.6 \times 10^{-11} \times 80 \times 50}{0.2 \times 0.2}$
= 6.6 × 10-6N