Moving Charges and Magnetism — Physics STD 12 Science — Question

An electron and a proton are at a distance of 1. The moment of this dipole will be (C  X m)

(a) 1.6

(b) 1.6

(c) 3.2

(d) 3.2

For intensity I of a light of wavelength 5000Å the photoelectron saturation current is 0.40 μA and stopping potential is 1.36 V, the work function of metal is

(a) 2.47 eV

(b) 1.36 eV

(c) 1.10 eV

(d) 0.43 eV

Two capacitors C₁ and C₂ = 2C₁ are connected in a circuit with a switch between them as shown in the figure. Initially the switch is open and C₁ holds charge Q. The switch is closed. At steady state, the charge on each capacitor will be

(a) Q, 2Q

(b) Q/3, 2Q/3

(c) 3Q/2, 3Q

(d) 2Q/3, 4Q/3

In a meter bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be 20 cm. The value of the unknown resistance is

(a) 0.8 Ω

(b) 0.5 Ω

(c) 0.4 Ω

(d) 0.25 Ω

An electron and a proton are in a uniform electric field, the ratio of their accelerations will be

(a) Zero

(b) Unity

(c) The ratio of the masses of proton and electron

(d) The ratio of the masses of electron and proton

In a semiconductor diode, the depletion region is removed when:

The focal lengths of the objective and eye-lens of a microscope are 1 cm and 5 cm respectively. If the magnifying power for the relaxed eye is 45, then the length  of the tube is

(a)  30 cm

(b)  25 cm

(c)  15 cm

(d)  12 cm

When a test charge is brought from infinity to near the dipole along the neutral line of an electric dipole, then the work done will be:

The idea of secondary wavelets for the propagation of a wave was first given by

(a) Newton

(b) Huygen

(c) Maxwell

(d) Fresnel

A potentiometer is an ideal device of measuring potential difference because

(a) It uses a sensitive galvanometer

(b) It does not disturb the potential difference it measures

(c) It is an elaborate arrangement

(d) It has a long wire hence heat developed is quickly radiated