The value of constant 'K' in coulomb law is _____________.

(a)

0.9 x 10⁹ Nm² C²

(b)

9 x 10^-9 Nm²C²

(c)

9 x 10⁹ Nm^-2 C^-2

(d)

9 x 10⁹ Nm² C^-2

An electron gun in a TV shoots out a beam of electrons. The beam current is 10\(\mu\)A. The charge that strikes the screen in 1 minute is ______________.

(a)

\(+600\mu C\)

(b)

\(-600\mu C\)

(c)

\(+10\mu C\)

(d)

\(-10\mu C\)

The direction of the magnetic force on a positive charge moving in a magnetic field is given by ________________.

(a)

thumb rule

(b)

left hand rule

(c)

right hand rule

(d)

cork screw rule

When the current flowing in a circular coil is doubled and the number of turns of the coil in it is halved, the magnetic field at its center will become _____________.

(a)

four times

(b)

same

(c)

half

(d)

double

An emf of 12V is induced when the current in the coil changes at the rate of 40 A S^-1. The coefficient of self-induction of the coil is _______________.

(a)

0.3 H

(b)

0.003 H

(c)

30 H

(d)

4.8 H

Speed of electromagnetic waves through vacuum is equal to ______________.

(a)

\(\sqrt { { \mu }_{ 0 }{ \varepsilon }_{ 0 } } \)

(b)

\(\frac { 1 }{ \sqrt { { \mu }_{ 0 }{ \varepsilon }_{ 0 } } } \)

(c)

\(\\ \frac { \sqrt { { \mu }_{ 0 } } }{ { \varepsilon }_{ 0 } } \)

(d)

\(\sqrt { \frac { { \varepsilon }_{ 0 } }{ { \mu }_{ 0 } } } \)

An object is at a distance of 0.5 in front of a plane mirror. Distance between the object and image is ___________.

(a)

0.5 m

(b)

1m

(c)

7

(d)

8

Photo electron effect supports quantum nature of light because ___________.

(a)

there is a minimum frequency which no photo electrons are emitted

(b)

the maximum kinetic energy of photo electrons depends only one the frequency of light and not in intensity

(c)

even when the metal surface is faintly illuminated the photoelectrons leave the surface immedietly

(d)

All the above

Electron microscope employ magnetic lenses of _______ focal lengths to obtain large magnification.

(a)

short

(b)

long

(c)

infinite

(d)

zero

An a-particle of energy 10 meV is scattered through 180^o by a fixed uranium nucleus. The distance of the closest approach is of the order of _____________.

(a)

1Å

(b)

10^-10 cm

(c)

10^-12 cm

(d)

10^-15 cm