Electric Charges and Fields — Physics STD 12 Science — Question

A steady electric current is flowing through a cylindrical conductor.

1. The electric field at the axis of the conductor is zero.
2. The magnetic field at the axis of the conductor is zero.
3. The electric field in the vicinity of the conductor is zero.
4. The magnetic field in the vicinity of the conductor is zero.

A transformer is employed to

(a) Obtain a suitable dc voltage	(b) Convert dc into ac
(c) Obtain a suitable ac voltage	(d) Convert ac into dc

The properties of a surface are different from those of the bulk liquid because the surface molecules:

1. Are smaller than other molecules.
2. Acquire charge due to collision from air molecules.
3. Find different type of molecules in their range of influence.
4. Feel a net force in one direction.

A photon of energy 3.4 eV is incident on a metal having work function 2 eV. The maximum K.E. of photo-electrons is equal to

(a) 1.4 eV

(b) 1.7 eV

(c) 5.4 eV

(d) 6.8 eV

A coil of inductance L is carrying a steady current i. What is the nature of its stored energy

(a)  Magnetic	(b)  Electrical
(c)  Both magnetic and electrical	(d)  Heat

The current in the following circuit is

(a)

(b)

(c)

(d) 1A

X-ray will travel minimum distance in

(a) Air

(b) Iron

(c) Wood

(d) Water

Energy required to remove an electron from aluminium surface is 4.2 eV. If light of wavelength 2000 Å falls on the surface, the velocity of the fastest electron ejected from the surface will be

(a) 8.4

(b) 7.4

(c) 6.4

(d) 8.4

In an electric circuit containing a battery, the charge (assumed positive) inside the battery:

Choose the correct answer from the alternatives given.
The conduction current is the same as displacement current when the source is.