The figure shows tow parallel equipotential surface A and B kept at a small distance 'r' a part from each other. A point change of Q coulomb is taken from the surface A to B. The amount of net work done will be 

(a)

\(W=\frac { -1 }{ 4\pi { \varepsilon }_{ 0 }r } \frac { q }{ r } \)

(b)

\(W=\frac { 1 }{ 4\pi { \varepsilon }_{ 0 }r } \frac { q }{ r } \)

(c)

\(W=\frac { -1 }{ 4\pi { \varepsilon }_{ 0 }r } \frac { q }{ r^2 } \)

(d)

zero

Two condensers (capacitors) of capacity C₁ and C₂ are connected in parallel. A charge Q given to then is shared. The ratio of the charges Q is _________

(a)

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

(b)

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

(c)

C₁.C₂

(d)

\(\frac { 1 }{ { C }_{ 1 }\times { C }_{ 2 } } \)

The expression for the electric field due to a surface of total charge 'Q' is given by __________

(a)

\(\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { \sigma dA }{ { r }^{ 2 } } } \hat { r } \)

(b)

\(\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { \rho dA }{ { r }^{ 2 } } } \hat { r } \)

(c)

\(\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { \lambda dl }{ { r }^{ 2 } } } \hat { r } \)

(d)

\(\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { dq }{ { r }^{ 2 } } } \hat { r } \)

The unit for electric flux is

(a)

C²N^-1m^-2

(b)

Nm²C^-2

(c)

Nm²C^-1

(d)

Nm^-2C^-1

The temperature co-efficient of resistance for alloys is _____________.

(a)

low

(b)

very low

(c)

high

(d)

very high

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

Electrical resistance is given by ___________________.

(a)

\(R=\cfrac { Al }{ \sigma } \)

(b)

\(R=\cfrac { l }{ \sigma A } \)

(c)

\(R=\cfrac { \sigma A }{ l } \)

(d)

\(R=\cfrac { \sigma }{ Al } \)

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

In Joule's law, when the current passed through the circuit is doubled keeping resistance (R) and time of passage of current (t) constant, temperature ______________.

(a)

increases twice

(b)

increases four times

(c)

increases sixteen times

(d)

decreases four times

The force on a proton moving with a speed of 10⁵ m/s perpendicular to a magnetic field 10^-3 tesla is ______

(a)

1.6 x 10^-17 N

(b)

1.6 x 10^-27 N

(c)

1.6 x 10^-19 N

(d)

10^-2 N

If a secondary coil has 40 turns, and a primary coil with 20 turns is charged with 50V of potential difference, then potential difference in secondary would be ________________.

(a)

50 V

(b)

25 V

(c)

60 V

(d)

100 V

Speed of electromagnetic wave is the same for all ______________.

(a)

wavelength

(b)

media

(c)

intensities

(d)

frequencies

Cellular phones use radio-waves in ______ band

(a)

long wave

(b)

ultra high frequency

(c)

short frequency

(d)

medium frequency

Two plane mirrors are at right angles to each other. A man stands between them and combs hair with his right hand. In how many of the images will he be seen using his right-hand __________.

(a)

None

(b)

1

(c)

2

(d)

3

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

Einstein's photoelectric equation is ____________.

(a)

W+hv=\(\frac{1}{2}\)mV²_max

(b)

\(\frac{1}{2}\)mV²_max=W

(c)

hv=hv₀+\(\frac{1}{2}\)mv²

(d)

2KE_max = hv - \(\phi\)

The wavelength associated with electrons on acceleration is generally of the order of metres is ________.

(a)

5 x 10^-12

(b)

6 x 10^-10

(c)

7 x 10^-9

(d)

60

When hydrogen atom is in its first excited level, its radius is __________ of the Bohr radius.

(a)

twice

(b)

same

(c)

half

(d)

four times

For first-order X-ray diffraction, the wavelength in of the X-ray is equal to the lattice spacing at a glancing angle is _____________.

(a)

15°

(b)

60°

(c)

45°

(d)

30°

The velocity of cathode rays is upto ________ the velocity of light.

(a)

0.10

(b)

0.001

(c)

10.5

(d)

0.01

Radio isotope _________ is used in the treatment of cancer.

(a)

sodium

(b)

cobalt

(c)

iron

(d)

phosphorous

The forward based diode is ______________.

(a)

(b)

(c)

(d)

The forbidden energy band gap in semi conductor, conductor and insulator are E₁, E₂ and E₃ respectively. The relation among them is _______________.

(a)

E₁. < E₂ > E₃

(b)

E₁ > E₂ > E₃

(c)

E₁ < E₂ < E₃

(d)

E₁ > E₂ < E₃

A light emitting diode has a voltage drop of 2v across it when 10 mA current is passed. If this LED is to be operated with 6v battery the value of limiting resistor would be ___________

(a)

400 Ω

(b)

4000 Ω

(c)

40 k Ω

(d)

300 Ω

Current gain in common emitter configuration is more than I because _______________.

(a)

IC < IE

(b)

IC < IB

(c)

IE > IB

(d)

IC > IE

When the output is an complement of the input it is ____________

(a)

NOT gate

(b)

AND gate

(c)

OR

(d)

NAND

Audio signal cannot be transmitted because _______________.

(a)

the signal has more noise

(b)

the signal cannot be amplitude for distance communication

(c)

the transmitting antenna length is very small to design

(d)

the transmitting antenna length is very large and impracticable

In an AM receiver, the local oscillator frequency is 2750 kHz. The tuned in station frequency is _____________.

(a)

2905 kHz

(b)

2295 kHz

(c)

3055 kHz

(d)

2250 kHz

The transmitter in a RADAR is a high power ________.

(a)

cyclotron oscillator

(b)

magnetron oscillator

(c)

Hartley oscillator

(d)

simple harmonic oscillator

_______ is synthesized top down approach

(a)

Ball milling

(b)

Plasma etching

(c)

lithography

(d)

Ball milling and lithography

In __________ it was established that atoms are made up of electrons, protons and neutrons

(a)

1945

(b)

1923

(c)

1930

(d)

1927