Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

Five lumen/watt is the luminous efficiency of a lamp and its luminous intensity is 35 candela. The power of the lamp is

(a) 80 W

(b) 176 W

(c) 88 W

(d) 36 W

Four condensers are joined as shown in the adjoining figure. The capacity of each is 8 μF. The equivalent capacity between the points A and  B will be

(a) 32  μF

(b) 2 μF

(c) 8 μF

(d) 16 μF

Current carrier in conductors is ____?

The number of photo electrons emitted for light of a frequency v (higher than the threshold frequency v₀​) is proportional to:

A galvanometer coil of resistance 50 W, show full deflection of 100 μA. The shunt resistance to be added to the galvanometer, to work as an ammeter of range 10 mA is

(a) 5 W in parallel

(b) 0.5 W in series

(c) 5 W in series

(d) 0.5 W in parallel

The work function of a metal is 1.6  J. When the metal surface is illuminated by the light of wavelength  6400 Å, then the maximum kinetic energy of emitted photo-electrons will be (Planck's constant h = 6.4 )

(a) 14

(b) 2.8

(c) 1.4

(d) 1.4

A wire can sustain the weight of 20kg before breaking. If the wire is cut into two equal parts, each part can sustain a weight of.

1. 10kg
2. 20kg
3. 40kg
4. 80kg.

In the adjoining circuit, the battery  has an e.m.f of 12 volt and zero internal resistance while the battery E has an e.m.f  of 2 volt. If the galvanometer G reads zero, then the value of the resistance X in ohm is

(a) 10

(b) 100

(c) 500

(d) 200

In Fresnel diffraction, if the distance between the disc and the screen is decreased, the intensity of central bright spot will

(a) Increase

(b) Decrease

(c) Remain constant

(d) None of these

A cell of e.m.f. E is connected with an external resistance R, then p.d. across cell is V. The internal resistance of cell will be

(a)

(b)

(c)

(d)