Physics Past Questions

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

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

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) \(5.0 \times 10^6 \mathrm{N}\)

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

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

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

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

Options

A) radioactivity

B) nuclear fusion

C) nuclear fission

D) chain reaction

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

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

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