Online Test

Question # 1

In young s interference experiment one slit is covered with a cellophane paper which absorbs half the intensity then

Choose an answer

No fringes are observed

All fringes will be darks

bright fringes will be less bright and dark will be less dark

Bright fringes will be brighter and dark fringes will be darks

The value of acceleration due to gravity on the surface of the earth is g.If the diameter of the earth becomes double of its present value and its mass remains unchanged, the value of acceleration due to gravity on the surface of the earth would become

Choose an answer

g/2

g/4

2g

4g

In common emitter amplifier, the input and output has phase shift

Choose an answer

90^o

180^o

No phase shift

None of these

Dolphin communicate with each other in sea by emitting

Choose an answer

Light signals

Audible sound

Ultrasonic waves

Infrasonic waves

The minimum frequency limit of the X-rays depends on

Choose an answer

Nature of target material

Kinetic energy of incident electrons

The degree of vacuum is Coolidge tube

None of these

A change in position of a body from its initial position to its final position is known as

Choose an answer

relative motion

displacement

distance

acceleration

An atom in which there is a resultant magnetic field behave like a

Choose an answer

Tiny magnet

Magnetic dipole

No magnet

a and b

A stress which decreases the stress along one dimension is known as:

Choose an answer

Compressive stress

Tensile stress

Linear stress

Both (B) and (C)

When the speed of a moving body is doubled

Choose an answer

Its P.E. is doubled

Its acceleration is doubled

Its K.E. is doubled

Momentum is doubled

Electric field force per unit charge is

Choose an answer

Coulomb's force

Electric intensity

Gauss's Law

None of these

A choke coil is used in

Choose an answer

A.C circuit only

D.C circuit only

A.C and D.C circuit

Neither A.C nor D.C.circuits

According to equation E = mc² Kg mass is actually the enrgy

Choose an answer

8 × 10¹⁵ J

9 × 10¹⁷ J

9 × 10¹⁶ J

8 × 10¹⁵ J

A fiber of 50μm diameter capable of carrying white light at ______ distances is called ______ index fiber

Choose an answer

Large, multi-mode step

Small, multi-mode step

Small, multi-mode graded

Large, single mode step

Aquifier is a layer of rock holding water that allows water to percolate through it with

Choose an answer

Temperature

Pressure

Steams

None of these

If rope of lift breaks suddenly,The tension exerted by the surface of lift is (a = Acceleration of lift)

Choose an answer

mg

m (g + a)

m (g - a)

0

A p-n junction is formed when a crystal of silicon is growth in such a way that its one half is doped with trivalent impurity and the other half with a impurity from

Choose an answer

2nd group

fourth group

fifth group

sixth group

The efficiency of carnot's engine can never be 1 or 100% unless cold reservoir is

Choose an answer

100 K

1 K°

0 K°

None of these

Which of these statements is not correct?

Choose an answer

Moment of inertia is independent of shape and size of the body

Moment of inertia depends on choice of axes

Moment of inertia does not depend on mass of body

None of these

In case of reflection of ray within a denser medium, angle of incidnet is ______ -angle of reflection

Choose an answer

Greater then

Smaller then

Equal to

None of these

The ratio of diameters of two convex lenses is ______ the ratio of their focal lengths

Choose an answer

Greater than

Less than

Equal to

Square of

Speed of sound in Iron at 20^oC is

Choose an answer

4570 ms^-1

5130 ms^-1

5140 ms^-1

6230 ms^-1

The crystalline structure of NaCl is

Choose an answer

rectangular

hexagonal

tetrahedral

cubical

The motion of a body in a straight line is the motion in

Choose an answer

one dimension

two dimensions

three dimensions

four dimensions

Which one of the following waves cannot be polarized

Choose an answer

Radio waves

X-rays

Transverse waves in a string

Longitudinal waves in a gas

In inductors, energy is stored due to

Choose an answer

magnetic field

electric field

flux density

none of them

For the treatment of skin cancers, the isotopes/isotopes are used

Choose an answer

Phosphorous-32

Strontium-90

Both

None of these

The approximate efficiency of liquid fuel rocket is

Choose an answer

49 %

50 %

48 %

47 %

Conditions for interference are that the two sources should be coherent and:

Choose an answer

At the far off distance

Close together

Coinciding

None of these

The output waveform obtained in full wave rectification is

Choose an answer

Pulsating

Somewhat pulsating

Not pulsating

None of these

The reactance of a coil changes directly with

Choose an answer

Frequency of a.c

The inductance

Both a and B

None of these

In which process, the change in internal energy of the system of zero:

Choose an answer

Isochoric process

isobaric process

Adiabatic process

Isothermal process

Speed of sound in hydrogen at 20°C is

Choose an answer

1286 ms^-1

1281 ms^-1

1287 ms^-1

1291 ms^-1

Five equal forces of 10N each are applied at one point and all are lying in one plane.If the angles between them are equal,the resultant force will be:

Choose an answer

Zero

10 N

20 N

10 √2 N

The drag force increase if the speed of the object moving through a fluid

Choose an answer

Increases

Decreases

remains constant

None of these

The S.I unit of decays constant is

Choose an answer

n^-1

kg^-1

A^-1

s^-1

For an adiabatic expansion of a gas which of the following statement is false?

Choose an answer

Pressure of gas decreases

No heat is supplied to the gas

Work is done by gas

Entropy of gas is increased

The Si unit of magnetic flux is

Choose an answer

Weber

Nm A^-1

N m^-1

Both A & B

The restoring force applied on the pendulum

Choose an answer

mg cos θ

mg sin θ

- mg sin θ

- mg cos θ

Torque will be zero if

Choose an answer

body is at rest

rotating with uniform angular velocity

zero angular acceleration

all of them

Heat rollers make the copy

Choose an answer

Heated

Tone melted

Dry

All of them

For a given angle of projection if the time of flight of a projectile is doubled the horizontal range will increases to:

Choose an answer

Four times

Thrice

Once

Twice