The torque experienced by a rectangular current loop placed perpendicular to a uniform magnetic field is

(a)

maximum

(b)

minimum

(c)

finite minimum

(d)

zero

Lenz's law is in accordance with the law of ________________.

(a)

conservation of charges

(b)

conservation of flux

(c)

conservation of momentum

(d)

conservation of energy

The efficiency of an ideal transformer is ____________.

(a)

0

(b)

1

(c)

infinite

(d)

none

The average power consumed per cycle is ______________.

(a)

Zero

(b)

2000 W

(c)

1000 W

(d)

500 W

An object is placed at 20 cm from a convex mirror of focal length 10 cm. The image formed by the mirror is _____________.

(a)

Real and 20 cm from the mirror

(b)

Virtual and at 20 cm from the mirror

(c)

Virtual and 20/3 cm from the mirror

(d)

Real and 20/3 cm from the mirror

Given a point source of light, which of the following can produce a parallel beam of light ______________.

(a)

Convex mirror

(b)

Concave mirror

(c)

Concave lens

(d)

Two plane mirrors inclined at an angle of 90°

A vehicle has a driving mirror of a focal length of 30 cm. Another vehicle of dimension 2 x 4 x 1.75 m³ is 9 m away from the mirror of the first vehicle. The position of the second vehicle as seen in the mirror of the first vehicle is ___________.

(a)

30 cm

(b)

60 cm

(c)

90 cm

(d)

9 cm

If the radius of third Bohr orbit in a hydrogen atom is r, then the de-Broglie wavelength of an electron in this orbit is ______________.

(a)

\(\frac { r }{ 3 } \)

(b)

3r

(c)

\(\frac { 2\pi r }{ 3 } \)

(d)

3(2πr)

The third electromagnet put in the path of an electron beam in an electron microscope is called _________

(a)

projector magnetic lens

(b)

accelerator

(c)

velocity selector

(d)

oscilloscope

If v = c, the mass of the moving body, of rest, mass 'm_o' is _________

(a)

zero

(b)

infinity

(c)

m_o

(d)

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

Find the accelerating potential of an electron whose de Broglie wave length is 3 Å

(a)

150.5 V

(b)

6.63 V

(c)

37.53 V

(d)

16.73 V

The de Broglie wavelength of electron accelerated with a potential V is ________

(a)

\(\lambda =\frac { h }{ \sqrt { Vem } } \)

(b)

\(\lambda =\frac { h }{ \sqrt { 2Vem } } \)

(c)

\(\lambda =\frac { h }{ m\sqrt { 2Vem } } \)

(d)

\(\lambda =\frac { h }{ m\sqrt { \frac { Ve }{ m } } } \)

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

The ionisation potential of hydrogen atom is ______________.

(a)

13.6eV

(b)

-13.6eV

(c)

13.6 V

(d)

-13.6 V

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

(a)

0.10

(b)

0.001

(c)

10.5

(d)

0.01

The charge of an alpha-particle is _______________

(a)

same as that of a proton

(b)

twice as that of an electron

(c)

thrice as that of an proton

(d)

twice as that of a neutron

The orbits in which electrons supposed to be revolving according to Rutherford are ___________

(a)

square-shaped

(b)

circular

(c)

rectangular

(d)

linear

The value of Bohr radius is _______ m.

(a)

53 x 10^-15

(b)

0.53 x 10^-12

(c)

53 x 10^-12

(d)

53 x 10^-15

When the electron jumps from any of the outer orbits to the first orbit, spectral lines are emitted in the ________ region.

(a)

visible

(b)

IR

(c)

X-ray

(d)

UV

If in a hydrogen spectrum, n₁ = 2 and n₂ = 3, 4, 5... then the series is called ___________ series.

(a)

Lyman

(b)

Balmer

(c)

Brackett

(d)

Pfund

Paschen series of hydrogen atom comes under ___________ region.

(a)

IR

(b)

UV

(c)

X-ray

(d)

Gamma ray

Energy of an atom at its ground state is ___________

(a)

zero

(b)

maximum

(c)

minimum

(d)

10 eV

The process of giving extra energy to an electron in an orbit is called ________ of the atom

(a)

grounding

(b)

excitation

(c)

sinking

(d)

induction

Which particle cannot be emitted by radioactive element during their decay?

(a)

neutrino

(b)

helium nuclei

(c)

photons

(d)

electrons

In gamma ray emission from nucli _____________.

(a)

both the neutron number and the proton number change

(b)

there is no change in neutron number and the proton number change

(c)

only the neutron number changes

(d)

only the proton number changes

Gamma rays are extensively used to destroy __________ affected cells

(a)

Sickle-cell anaemia

(b)

Cancer

(c)

HIV

(d)

Polio virus

In the nuclear reaction ₄Be⁹ + X ➝ ₆C¹² + ₀n¹ X stands for ______________.

(a)

proton

(b)

α particle

(c)

electron

(d)

deutron

Roentgen (R) is the unit to measure _________

(a)

X-ray strength

(b)

number of holes produced by X-rays

(c)

radiation exposure

(d)

number of cancer cells

To convert fertile material into fissile material, we make use of _______ reactors.

(a)

research

(b)

production

(c)

power

(d)

generator

_______ is synthesized top down approach

(a)

Ball milling

(b)

Plasma etching

(c)

lithography

(d)

Ball milling and lithography

Which statement is incorrect regarding for p-n junction?

(a)

Donor atoms are depleted of their holes in junction

(b)

No net charge exists far from junction

(c)

Barrier potential V_B is generated

(d)

Energy V_B is to be surrounted before any charge can flow across junction

In an N-P-N transistor circuit, the emitter, collector, and base current are respectively I_E, I_C, and l_B. The relation between them is _____________.

(a)

I_C EB

(b)

I_B CE

(c)

I_B > I_C > I_E

(d)

I_B > I_C > I_E

In an P.N.P transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector _____________.

(a)

I_E = 9mA

(b)

I_E = 10mA

(c)

I_B = 1mA

(d)

I_B = - 1mA

Which of the following figure represents an ideal diode characteristics?

(a)

(b)

(c)

(d)

For Boolean identities match the pair
(i) \(\overset { = }{ A } \) (P) Ā + \(\bar { B } \)
(ii) \(\overline { A+B } \) (Q) A.B
(iii) \(\overline { A.B } \) (R) \(\bar { A } .\bar { B } \)
(iv) A.(Ā + B) (S) A

(a)

1 - (S), 2 (P), 3 - (Q), 4 - (R)

(b)

1 - (S), 2 (R), 3 - (Q), 4 - (P)

(c)

1 - (S), 2 (Q), 3 - (P), 4 - (R)

(d)

1- (S), 2 (R), 3 - (P), 4 - (Q)

The process of increasing the strength of a signal using an electric circuit is called ________________.

(a)

amplification

(b)

modulation

(c)

demodulation

(d)

transmission

Ground wave have wavelength ________________.

(a)

less than that of sky waves

(b)

greater than that of sky wave

(c)

less than that of space waves

(d)

equal to that of space waves

When NPN transistor is used as an amplifier then _____________

(a)

electron moves from base to collector

(b)

hole travels from emitter to base

(c)

hole goes to emitter from base

(d)

electron goes to base from collector

In space communication, the sound waves can be sent from one place to another ________.

(a)

through space

(b)

through wires

(c)

by super imposing it on undamped EM waves

(d)

by super imposing it on damped EM waves

Doping of a semiconductor generally changes resistivity as follows ________________.

(a)

increases

(b)

decreases

(c)

does not alter

(d)

may increase

Skip distance the shortest distance between ______________.

(a)

the point of transmission and the point of reception

(b)

the uplink and the downlink station

(c)

the transmitter and the target

(d)

the receiver and the target

The process of superimposing the audio signal over the carrier wave is called ________

(a)

superposition

(b)

modulation

(c)

demodulation

(d)

extraction

The radiation of electrical energy is practicable only above _________

(a)

20 kHz

(b)

200 MHz

(c)

200 kHz

(d)

20 Hz

Reverse bias applied to a junction diode is ______________.

(a)

increases the potential barrier

(b)

increases the majority carrier current

(c)

lowers the potential barrier

(d)

increases the minority carrier current

If the distance between the conduction band and valence band is leV, then this combination is _______________.

(a)

semiconductor

(b)

metal

(c)

insulator

(d)

conductor

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

(a)

signal swing

(b)

carrier swing

(c)

shift

(d)

difference

In a transmitter, the _______ isolates the RF amplifier from the oscillator.

(a)

amplifier

(b)

oscillator

(c)

buffer

(d)

transistor

The ability to select a particular wanted signal only and rejecting the unwanted signals is called __________.

(a)

sensitivity

(b)

buffer action

(c)

reception

(d)

selectivity

Vacant energy levels are called _________

(a)

valence level

(b)

core level

(c)

conduction levels

(d)

compound level

The speaker converts ________ energy into ______ energy.

(a)

electrical, sound

(b)

sound, electrical

(c)

light, sound

(d)

sound, mechanica