Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric flux through each Gaussian surface in increasing order.

(a)

D < C < B < A

(b)

A < B = C < D

(c)

C < A = B < D

(d)

D > C > B > A

In a parallel plate capacitor of capacitance C, a metal sheet is inserted between the plates, parallel to them. The thickness of the sheet is half of the separation between the plates. The capacitance now becomes

(a)

2C

(b)

\(\frac{C}{4}\)

(c)

4C

(d)

\(\frac{C}{2}\)

In a hollow spherical shell potential (V) changes with respect to distance (r) from centre.
\(\left[ { V }_{ inside }=\frac { Q }{ 4\pi { \varepsilon }_{ 0 }R } r\le R,\quad { V }_{ outside }=\frac { Q }{ 4\pi { \varepsilon }_{ 0 }r } r\ge R,V\alpha \frac { 1 }{ r } \right] \)

(a)

(b)

(c)

(d)

Two wires of A and B with circular cross section made up of the same material with equal lengths. Suppose R_A = 3 R_B, then what is the ratio of radius of wire A to that of B?

(a)

3

(b)

\(\sqrt3\)

(c)

\(\frac{1}{\sqrt3}\)

(d)

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

When the free electrons are moving in all possible directions, the value of the current produced is_______

(a)

lA

(b)

2A

(c)

0 A

(d)

1.2A

The BH curve for a ferromagnetic material is shown in the figure. The material is placed inside a long solenoid which contains 1000 turns/cm. The current that should be passed in the solenoid to demagnetize the ferromagnet completely is _____.

(a)

1.00 m A

(b)

1.25 mA

(c)

1.50 mA

(d)

1.75 mA

A galvanometer can be converted into a voltmeter by connecting _________________.

(a)

a low resistance in parallel to it

(b)

a high resistance in parallel to it

(c)

a low resistance in series with it

(d)

a high resistance in series with it

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

During the propagation of electromagnetic waves in a medium __________________.

(a)

electric energy density is double of the magnetic energy density

(b)

electric energy density is half of the magnetic energy density

(c)

electric energy density is equal to the magnetic energy density

(d)

both electric and magnetic energy densities are zero

Electromagnetic waves are __________ waves.

(a)

longitudinal

(b)

Transverse

(c)

mechanical

(d)

sound

The relation between velocity of light, permeability and permittivity of free space in________.

(a)

\({ C }^{ 2 }=\frac { 1 }{ { \mu }_{ 0 }{ \varepsilon }_{ 0 } } \)

(b)

\(C=\frac { 1 }{ { \mu }_{ 0 }{ \varepsilon }_{ 0 } } \)

(c)

\({ \mu }_{ 0 }={ \varepsilon }_{ 0 }c\)

(d)

\({ \varepsilon }_{ 0 }={ \mu }_{ 0 }c\)

_________ spectra are used for making dyes

(a)

continuous emission

(b)

band emission

(c)

band absorption

(d)

line spectra

In a Young’s double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to, _____.

(a)

2D

(b)

\(\frac{D}{2}\)

(c)

\(\sqrt{2}\)D

(d)

\(\frac{D}{\sqrt2}\)

In photoelectric emission, a radiation whose frequency is 4 times threshold frequency of a certain metal is incident on the metal. Then the maximum possible velocity of the emitted electron will be _____.

(a)

\(\sqrt { \frac { { hv }_{ o } }{ m } } \)

(b)

\(\sqrt { \frac { { 6hv }_{ o } }{ m } } \)

(c)

\(2\sqrt { \frac { { hv }_{ o } }{ m } } \)

(d)

\(\sqrt { \frac { { hv }_{ o } }{2m } } \)

According to Einstein's photoelectric equation the graph between the K.E of photoelectrons ejected and the frequency of incident radiation is ____________.

(a)

(b)

(c)

(d)

The energy of the electron in the first orbit of hydrogen atom is -13.6 eV. Its potential energy is _______________.

(a)

-13.6 eV

(b)

13.6eV

(c)

-27.2 eV

(d)

27.2 eV

The principle based on which a solar cell operates is______.

(a)

Diffusion

(b)

Recombination

(c)

Photovoltaic action

(d)

Carrier flow

A current gain for, a transistor working as CB amplifier is 0.90. If emitter current is 10 mA, then base current is ________________.

(a)

1mA

(b)

2 mA

(c)

0.1 mA

(d)

0.2 mA

A p-n diode can be used as _______________.

(a)

condenser

(b)

amplifier

(c)

rectifier

(d)

regulator

In modulation process radio frequency wave is termed as ______________.

(a)

modulated wave

(b)

modulating wave

(c)

carrier wave

(d)

none

After the angle of refraction becomes 90^o at the ionosphere, the wave travels _________.

(a)

faster

(b)

through space

(c)

in a straight line

(d)

towards the earth

The total variation in frequency of a FM transmitter is called _______

(a)

signal swing

(b)

carrier swing

(c)

shift

(d)

difference

In actual practice, the range of uplink frequencies used is _________ GHz.

(a)

5.725 - 7.075

(b)

3.4 - 4.8

(c)

6 - 10

(d)

9 - 10

The blue print for making ultra durable synthetic material is mimicked from _____.

(a)

Lotus leaf

(b)

Morpho butterfly

(c)

Parrot fish

(d)

Peacock feather

George Devel invented the first digitally operated programmable robot called ____________.

(a)

Unimate

(b)

Robotics

(c)

Motors

(d)

Generators