Practice paper · Bengaluru region

A point charge q is kept at a distance r from an infinitely long straight wire with charge density λ. The magnitude of the electrostatic force experienced by charge q is

1. AZero
2. Bqλ/(2πϵ₀r)
3. Cqλ/(4πϵ₀r)
4. Dqλ/(ϵ₀r)

Shape of equipotential surfaces in uniform electric field will be :

1. ASpherical normal to electric field
2. BRandom
3. CCircular normal to electric field
4. DEquidistant Planes normal to electric field.

The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then

1. Athe resistance and the specific resistance, will both remain unchanged
2. Bthe resistance will be doubled and the specific resistance will be halved
3. Cthe resistance will be halved and the specific resistance will remain unchanged
4. Dthe resistance will be halved and the specific resistance will be doubled

Magnetic field lines inside an ideal solenoid are:

1. ACircular
2. BStraight and parallel
3. CRandom
4. DPerpendicular to the axis

Identify the property which is not characteristic for a semiconductor?

1. Aat a very low temperatures, it behaves like an insulator
2. Bat higher temperatures two types of charge carriers will cause conductivity
3. Cthe charge carriers are electrons and holes in the valence band at higher temperatures
4. Dthe semiconductor is electrically neutral.

Two thin lenses are in contact and the focal length of the combination is 80 cm. If the focal length of one lens is 20 cm, then the power of the other lens will be

1. A1.66 D
2. B4.00 D
3. C– 100 D
4. D– 3.75 D

When radiation of given frequency is incident upon different metals, the maximum kinetic energy of the electrons emitted electrons

1. Adecreases with increase of work function
2. Bincreases with increase of work function
3. Cremains same with the increase of work function
4. Ddoes not depend upon work function