Two identical conducting balls having positive charges q₁ and q₂ are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be _____.

(a)

less than before

(b)

same as before

(c)

more than before

(d)

zero

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

Which one of the following relation is correct?

(a)

V = \(\frac{q}{C}\)

(b)

C = q tan q

(c)

V = qC

(d)

\(\frac{V}{C}\)

A toaster operating at 240 V has a resistance of 120 Ω. The power is ______.

(a)

400 W

(b)

2 W

(c)

480 W

(d)

240 W

A metallic block has no potential difference applied across it, then the mean velocity of free electrons is _____________.

(a)

proportional to T

(b)

proportional for \(\sqrt { T } \)

(c)

finite but independent of temperature

(d)

zero

A potential difference is applied an the ends of a metallic wire. If the potential difference is doubled, the drift velocity ________________.

(a)

will be doubled

(b)

will be halved

(c)

will be quadrupled

(d)

will remain unchanged

Fuse wire is an alloy of

(a)

37 % lead and 63 % tin

(b)

63 % lead and 37 % tin

(c)

37 % copper and 63 % tin

(d)

63 % copper and 37 % tin

5A of current flowing through a resistor for 2 minute produces 3000 j of heat. The value of the resistance is ____________.

(a)

1\(\Omega \)

(b)

2\(\Omega \)

(c)

4\(\Omega \)

(d)

5\(\Omega \)

The specific resistance for the insulators is in the range of________

(a)

10^-610-⁸\(\Omega m\)

(b)

10⁸-10¹⁴\(\Omega m\)

(c)

10^-8-10^-14\(\Omega m\)

(d)

10^-8-10¹⁴\(\Omega m\)

Kirchhoff's I law is a consequence of__________

(a)

law of conservation of energy

(b)

law of conservation of charges

(c)

law of conservation of currents

(d)

law of conservation of voltages

An electron moves in a straight line inside a charged parallel plate capacitor of uniform charge density σ. The time taken by the electron to cross the parallel plate capacitor undeflected when the plates of the capacitor are kept under constant magnetic field of induction  \((\vec{B})\) is

(a)

\({ \varepsilon }_{ ° }\frac { elB }{ \sigma } \)

(b)

\({ \varepsilon }_{ ° }\frac { lB }{ \sigma {l} } \)

(c)

\({ \varepsilon }_{ ° }\frac { lB }{ {e}\sigma } \)

(d)

\({ \varepsilon }_{ ° }\frac { lB }{ \sigma } \)

A current carrying conductor is associated with  _______________.

(a)

electric field

(b)

magnetic field

(c)

electro magnetic

(d)

all these

According to Joule's heating effect the law of resistance is _______________. 

(a)

H ∝ R

(b)

H ∝ R²

(c)

R ∝ H²

(d)

all the above

Which one of the following equation is correct with respect to an ammeter?

(a)

I_gG = I_gS

(b)

(I - I_g) G = I_gS

(c)

I_gG = (I - I_g)S

(d)

I_gG = (I + I_g)S

The flux linked with a coil at any instant t is given by \(\Phi\)_B = 10t² − 50t + 250. The induced emf at t = 3s is

(a)

−190 V

(b)

−10 V

(c)

10 V

(d)

190 V

In an electromagnetic wave traveling in free space the rms value of the electric field is 3 V m⁻¹. The peak value of the magnetic field is _____.

(a)

1.414 x 10^-8 T

(b)

1.0 x 10^-8 T

(c)

2.828 x 10^-8 T

(d)

2.0 x 10^-8 T

The existence of E.M. waves was confirmed experimentally by __________________.

(a)

Hertz

(b)

Maxwell

(c)

Huygens

(d)

Planck

Stars twinkle due to, ______.

(a)

reflection

(b)

total internal reflection

(c)

refraction

(d)

polarisation

When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the same surface is illuminated with radiation of wavelength 2λ, the stopping potential is \(\frac{V}{4}\). The threshold wavelength for the metallic surface is _____.

(a)

4λ

(b)

5λ

(c)

\(\frac{5}{2}λ\)

(d)

3λ

In J.J. Thomson e/m experiment, electrons are accelerated through 2.6 kV enter the region of crossed electric field and magnetic field of strength 3.0 x 10⁴ Vm^-1 and 1.0 x 10^-3 T, respectively, and pass through it and undeflected, then the specific charge is _____.

(a)

1.6 × 10¹⁰ C kg^–1

(b)

1.7 × 10¹¹ Ckg^–1

(c)

1.5 × 10¹¹ Ckg^–1

(d)

1.8 × 10¹¹ Ckg^–1

The minimum wavelength of the X-rays produced by electrons accelerated through a potential difference of V volts is directly proportional to _____________.

(a)

\(\frac { 1 }{ \sqrt { V } } \)

(b)

\(\frac { 1 }{ V } \)

(c)

\(\sqrt { V } \)

(d)

V²

The principle based on which a solar cell operates is______.

(a)

Diffusion

(b)

Recombination

(c)

Photovoltaic action

(d)

Carrier flow

For a transistor \(\frac{I_C}{I_E}\) = 0.96, then CE current gain is ______________.

(a)

12

(b)

6

(c)

24

(d)

48

The internationally accepted frequency deviation for the purpose of FM broadcasts ____________.

(a)

75 kHz

(b)

68 kHz

(c)

80 kHz

(d)

70 kHz

The gravitational waves were theoretically proposed by _____.

(a)

Conrad Rontgen

(b)

Marie Curie

(c)

Albert Einstein

(d)

Edward Purcell