The relative permittivity of water is _______.

(a)

ε_r = 70

(b)

ε_r = 75

(c)

ε_r = 80

(d)

ε_r = 85

The force experienced by a unit charge is called ____________

(a)

Electric potential

(b)

Electric flux

(c)

Electric field

(d)

Static electricity

Two charges are kept at a distance in air what should be the relative permittivity of the medium in which the two charges should be kept at the same distance so that they experience half of the force which they experienced in air?

(a)

\(\frac{1}{2}\)

(b)

\(\frac{1}{0.2}\)

(c)

2

(d)

0.2

For continuous charge distributions, _____ methods can be used.

(a)

integration

(b)

differentiation

(c)

multiplication

(d)

addition

Two charged bodies of charges +q, -3q are brought in contact and separated. The charges prossed by each body after separation.

(a)

-q,-q

(b)

+q,-2q

(c)

-q, +3q

(d)

q, q

If the specific resistance of a potentiometer wire is 10^-7 Om and current flowing through it is 0.1 amp, cross-sectional area of wire is 10^-6 m², then potential gradient will be ________________.

(a)

10^-2 v/m

(b)

10^-4 v/m

(c)

10^-6 v/m

(d)

10^-8v/m

A bird sitting on an insulated wire carrying a current feels quite safe because ____________.

(a)

the bird is a non-conductor of electricity

(b)

resistance of the bird is very large

(c)

there is a large potential difference between bird and wire

(d)

there is no potential difference between bird and wire

Which material is having a small value of temperature coefficient of resistance?

(a)

copper

(b)

constantan or manganin

(c)

nichrome

(d)

both b & c

Thermo electric generators are used in power plants to convert_________ into electricity.

(a)

light energy

(b)

waste heat

(c)

sound energy

(d)

hydro energy

In a carbon resistor, the third ring represents___________

(a)

powers of zeros

(b)

powers of ten

(c)

ten

(d)

infinity

The most suitable metal for permanent magnet is ______________.

(a)

copper

(b)

aluminium

(c)

steel

(d)

iron

Graph of force per unit length between long parallel current-carrying conductors, and the distance between them is ______________.

(a)

straight line

(b)

parabola

(c)

ellipse

(d)

rectangular hyperbola

A 110 W, 220 V bulb draws a current _______________.

(a)

2 A

(b)

440 A

(c)

0.5 A

(d)

5.5 A

In a tangent galvanometer a current 1A, produces deflection of 30° the current required to produce a deflection of 60° is ______________________.

(a)

3A

(b)

2A

(c)

\(\sqrt { 2 } \)

(d)

\(\frac { 1 }{ \sqrt { 3 } } \)A

The angular momentum of an electron revolving in second order (n = 2) is _________________.

(a)

6.6 x 10^-34 Js

(b)

3.3 x 10^-34 Js

(c)

2.1 x 10^-34 Js

(d)

9.27 x 10^-34 Js

An α-particle enters a magnetic field of 1T with a velocity 10⁶ m/s in a direction perpendicular to the field. The force on α-particle is _____________________.

(a)

1.6 x 10^-13N

(b)

6.4  x 10^-13N

(c)

4.8  x 10^-13N

(d)

3.2  x 10^-13N

The elements having Thomson positive effect are ________

(a)

Sb, Hg, Zn

(b)

Ag, Hg, Cd

(c)

Zn, Cd, Sb

(d)

Cd, Pt, Ag

Torque acting on a coil is maximum when the coil is ______

(a)

parallel to the magnetic field

(b)

perpendicular to the magnetic field

(c)

at an angle of 45° to the magnetic field

(d)

at any position in a uniform magnetic field

The magnitude of the induced emf in a conductor depends on the _______________.

(a)

flux density of the magnetic field

(b)

amount of flux cut

(c)

amount of flux linkages

(d)

rate of change of flux

Flux loss can be minimized using ________ core.

(a)

laminated

(b)

shell-type

(c)

perforated

(d)

sheet-type

The electric and magnetic field of an EM wave are _____________.

(a)

in phase and perpendicular to each other

(b)

in phase and parallel to each other

(c)

in opposite phase and perpendicular to each other

(d)

in opposite phase and parallel to each other

A red flower seen in the light of mercury vapour lamp through a green filter will appear ________________.

(a)

black

(b)

red

(c)

violet

(d)

white

________ radiations are used to study atomic structure.

(a)

UV

(b)

IR

(c)

X-rays

(d)

Gamma

A ray of light is incident normally on a lane mirror. The angle of reflection will be _____________.

(a)

0°

(b)

90°

(c)

will not be reflected

(d)

None of these

A diminished virtual image can be formed only in ______________.

(a)

Plane mirror parabolic mirror

(b)

A concave mirror

(c)

A convex mirror

(d)

concave

A point object is moving on the principal axis of a concave mirror of focal length 24 cm towards the mirror. When it is at a distance of 60 cm from the mirror, its velocity is 9 cm/ sec. what is the velocity of the image at that instant?

(a)

5 cm/see toward the mirror

(b)

4 cm/see towards the mirror

(c)

4 cm/see away from the mirror

(d)

9 cm/see away from the mirror

Stopping potential of emitted photo electrons is given by (where ф = hv₀) _____________.

(a)

\(\frac { hv-{ \phi }_{ 0 } }{ e } \)

(b)

hv-ф

(c)

\(\frac { hv }{ e } \)

(d)

\(\frac { hv+{ \phi }_{ 0 } }{ e } \)

When the momentum of a particle increases the de Broglie wavelength is ______________.

(a)

increases

(b)

decreases

(c)

does not change

(d)

infinity

______ theory explains photo electric effect.

(a)

Electromagnetic

(b)

Quantum

(c)

Wave

(d)

Corpuscular

An oil drop carrying a charge q has a mass of m kg. It is falling freely in the air with terminal speed v. The electric field required to make the drop move upwards with the same speed is ______________.

(a)

\(\frac{mg}{q}\)

(b)

\(\frac{2mg}{q}\)

(c)

\(\frac{mgv}{q^2}\)

(d)

\(\frac{2mgv}{q}\)

The ground-state energy of hydrogen atom is ____________ eV

(a)

-13.6

(b)

-18.7

(c)

18.6

(d)

\(\frac{1}{13.6}\)

The behaviour of Ge as semi-conductor is due to width of ___________.

(a)

conduction band being large

(b)

forbidden band being small

(c)

conduction band being small

(d)

forbidden band being small and narrow

The cause of potential barrier in a p-n diode is ________________.

(a)

depletion of negative charges near the junction

(b)

concentration of positive charges near the junction

(c)

depletion of positive charges near the junction

(d)

concentration of positive and negative charges near the junction

The radio waves of frequency 30 MHz to 300 MHz belong to _______________.

(a)

high frequency band

(b)

very high frequency band

(c)

ultra high frequency band

(d)

super high frequency band

Muscle wires can contract by _________ when electric current is passed through them.

(a)

5%

(b)

7%

(c)

25%

(d)

50%