Ray Optics and Optical Instruments — Physics STD 12 Science — Question

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

When light travels from one medium to the other of which the refractive index is different, then which of the following will change

(a) Frequency, wavelength and velocity	(b) Frequency and wavelength
(c) Frequency and velocity	(d) Wavelength and velocity

Best neutron moderator is

(a) Berillium oxide

(b) Pure water

(c) Heavy water

(d) Graphite

In a semiconductor diode, the barrier potential offers opposition to:

Five capacitors of 10 μF capacity each are connected to a d.c. potential of 100 volts  as shown in the adjoining figure. The equivalent capacitance between the points  A and B will be equal to

(a) 40 μF

(b) 20 μF

(c) 30 μF

(d) 10 μF

A small circular coil of radius 1cm and number of turns 100 is placed inside a long solenoid of radius 5cm and number of turns 8per cm. The axis of the coil is parallel to the solenoid axis. Then, the coefficient of mutual inductance of the two coils is (in milli Henry).

What happens when the end of the paper clip of electroscope is touched by hands?

A nucleus of   originally at rest emits a particle with speed v. What will be the recoil speed of the daughter nucleus

(a) 4v/206

(b) 4v/214

(c) v/206

(d) v/214

The ground state energy of hydrogen atom is – 13.6 eV. What is the potential energy of the electron in this state

(a) 0 eV

(b) – 27.2 eV

(c) 1 eV

(d) 2 eV