Nuclei — Physics STD 12 Science — Question

Figure shows some equipotential lines distributed in space. A charged object is moved from point A to point B.

Which of the following graphs shows the variation of magnetic induction B with distance r from a long wire carrying current

(a)

(b)

(c)

(d)

A transistor is used in common emitter mode as an amplifier. Then

(a) The base-emitter junction is forward biased

(b) The base-emitter junction is reverse biased

(c) The input signal is connected in series with the voltage applied to the base-emitter junction

(d) a, c

When light is refracted into a medium:

1. Its wavelength and frequency both increase
2. Its wavelength increases but frequency remains unchanged
3. Its wavelength decreases but frequency remains unchanged.
4. Its wavelength and frequency both decrease.

In photoelectric effect if the intensity of light is doubled then maximum kinetic energy of photoelectrons will become

(a) Double

(b) Half

(c) Four time

(d) No change

A foil of aluminium of negligible thickness is inserted in between the space of a parallel plate condenser. If the foil is electrically insulated, the capacity of the condenser will:

The self-induced e.m.f. in a 0.1 H coil when the current in it is changing at the rate of 200 ampere/second  is

(a) 8

(b) 8

(c) 20 V

(d) 125 V

A particle of mass 0.6 g and having charge of 25 nC is moving horizontally with a uniform velocity 1.2   in a uniform magnetic field, then the value of the magnetic induction is  

(a) Zero

(b) 10 T

(c) 20 T

(d) 200 T

The absorption of radio waves by the atmosphere depends upon:

Capacitance (C) of the capacitor is.