Moving Charges and Magnetism — Physics STD 12 Science — Question

A battery of emf 10 V and internal resistance 3Ω is connected to a resistor as shown in the figure.  If the current in the circuit is 0.5 A.  then the resistance of the resistor will be

(a) 19 W

(b) 17 W

(c) 10 W

(d) 12 W

Boron rods in nuclear reactor are used as a

(a) Moderator

(b) Control rods

(c) Coolants

(d) Protective shield

The work function is called:

The number of electrons to be put on a spherical conductor of radius 0.1m to produce an electric field of 0.036 N/C  just above its surface is

(a) 2.7

(b) 2.6

(c) 2.5

(d) 2.4

The colour sequence in a carbon resistor is red, brown, orange and silver. The resistance of the resistor is

(a) 21 × 103 ± 10%

(b) 23 × 101 ± 10 %

(c) 21 × 103 ± 5%

(d) 12 × 103 ± 5%

A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The e.m.f. of the cell needed to make the bulb glow at full intensity is

(a) 4.5 V

(b) 1.5 V

(c) 2.67 V

(d) 13.5 V

Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due to:

Four plates of equal area A are separated by equal distances d and are arranged as shown in the figure. The equivalent capacity is

(a)

(b)

(c)

(d)

The spectral series of the hydrogen spectrum that lies in the ultraviolet region is the

(a) Balmer series

(b) Pfund series

(c) Paschen series

(d) Lyman series

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