Electric Charges and Fields — Physics STD 12 Science — Question

Stopping potential for photoelectrons

(a) Does not depend on the frequency of the incident light

(b) Does not depend upon the nature of the cathode material

(c) Depends on both the frequency of the incident light and nature of the cathode material

(d) Depends upon the intensity of the incident light

In a discharge tube at 0.02 mm, there is a formation of

(a) FDS

(b) CDS

(c) Both space

(d) None of these

The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 mT. What will be its value at the centre of the loop

(a) 250 m T

(b) 150 m T

(c) 125 m T

(d) 75 m T

A bar magnet A of magnetic moment M_A is found to oscillate at a frequency twice that of magnet B of magnetic moment M_B when placed in a vibrating magneto-meter. We may say that

(a)

(b)

(c)

(d)

The ratio of the energy of an X-ray photon of wavelength 1 Å to that of visible light of wavelength 5000 Å  is

(a) 1: 5000

(b) 5000 : 1

(c) 1 :25  × 106

(d) 25 × 106

The velocity of photon is proportional to (where n is frequency)

(a)

(b)

(c)

(d) n

The network shown in the figure is a part of a complete circuit. If at a certain instant the current i is 5 A and is decreasing at the rate of   then   is

(a) 5 V

(b) 10 V

(c) 15 V

(d) 20 V

In Young's double slit experiment the intensity of the maxima is I. If the width of each slit is doubled, the intensity of the maxima will be:

If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be

(a) 50 Hz

(b) 70.7 Hz

(c) 100 Hz

(d) 25 Hz

Two sound waves move in the same direction in the same medium. The pressure amplitudes of the waves are equal but the wavelength of the first wave is double the second. Let the average power transmitted across a cross-section by the first wave be P₁ and that by the 1 second wave be P₂. Then,

1. P₁ = P₂
2. P₁ = 4P₂
3. P₂ = 2P₁
4. P₂ = 4P₁