Online Test

Question # 1

Thermistors are components which convert temperature changes into

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electrical current

electrical resistance

electrical voltage

none of them

When scattered X-ray photons are observed at θ = 90^o, the Compton shift Δλ equal to

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Compton shift

Compton wavelength

Full wavelength

None of these

An elastic spring has a mass m suspended from its lower end. Its time period is T when set into vibrations its time period in conditions of weightlessness is

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2T

Zero

Infinity

T

Pressure exerted by a gas is

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Independent of density of the gas

Inversely proportional to the density of the gas

Directly proportional to the square of the density of the gas

Directly proportional to the density of the gas

To get p-type semiconductor we add impurity from

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3^rd group

4^th group

5^th group

6^th group

Which of the following is the most common method to obtain polarized light?

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selective absorption

reflection from different surfaces

refraction through crystals

scattering by small particles

At what point/points in its path does a projectile have its maximum speed

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At the point of projection

At the point where its strikes the ground

Both

None of these

The time of flight of a projectile motion equal to

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half of the time to reach maximum height

twice the time to reach maximum height

one fourth of time to reach maximum height

time to reach maximum height

The wave speed is given by

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v = Tλ

v = fλ

v= f/λ

None of these

The number of significant figures in 5850 is

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3

4

5

2

The binding energy per nucleon of U²³⁵

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7 MeV

7.5 MeV

7.6 MeV

8 MeV

The resistivity ρ of Tungston in Ωm is

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4.00 × 10^-8

4.8 × 10^-8

5.00 × 10^-8

None of these

In normal adjustment, the length of the telescope is

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f_e + f_o

f_o - f_e

f_e - f_o

None of these

An electron moves at 2 X 10²m/sec perpendicular to magnetic field of 2T what is the magnitude field is:

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1 X 10^-6N

6.4 X 10^-17N

3.6 X 10^-24N

4 X 10⁶N

A ball is dropped vertically down and it takes time t to reach the ground.At time t/2:

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The hall had covered exactly half the distance

The velocity of the ball was V/3 where V is the velocity when it reached the ground

The ball had covered less than half the distance

The ball had covered more than half the distance

If a stretched string of length 'I' is plucked from its centre, this gives rise to

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longitudinal waves

sound

stationary waves

none of them

The fractional effect between layers of following fluid is

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Viscosity of fluid

Velocity of fluid

Acceleration of fluid

Pressure of fluid

The angular momentum of a system of particles is not conserved

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When net external force is acting upon the system

When a net external torque is acting upon the system

When a net external impulse is acting upon the system

None of these

In a three phase A.C generator the phase difference between each pair of coils is

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90°

180°

120°

140°

An α-particle enters a magnetic field of 1 tesla with a velocity 10⁶ m/s in a direction perpendicular to the field.The force on α-particle is

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1.6 x 10^-13 N

6.4 x 10^-13 N

4.8 x 10^-13 N

3.2 x 10^-13 N

In YDS experiment, data given isλ= 500 nm, L = 100 cm,Δy comes out to be

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0.5 cm

0.5 mm

0.5 nm

0.5 m

An atom in which there is a resultant magnetic field, behaves like a tiny magnet and is called as

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magnetic

magnetic dipole

magnetic monopole

none of them

Moment of inertia of a sphere is

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1/3 mr²

3/4 mr²

4/5 mr²

2/5 mr²

Typical source of β-particle is

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Radon 222

Cobalt 62

Strontium 94

None of these

The path followed by a ballistic missile is called

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parabolic trajectory

ballisitic trajectory

both of them

none of them

When a silicon crystal is doped with trivalent impurity which are

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Indium

Arsenic

Phosphorous

None of these

The wave is generated by an oscillation in the vibrating body and propagation of wave an through space is by means of oscillation are

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Electric and magnetic waves

Mechanical waves

Water waves

None of these

The photograph taken by the electron microscope is known as

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Photograph

Electron micrograph

Chronograph

None of these

A system in which there is no transfer of mass across the boundary is called

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An isolated system

A closed system

An open system

None of these

Neutrons are particularly more damaging to

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Legs

Heart

Eyes

Brain

The original source of solar energy is

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Moon

Sun

Stars

Earths

In n-type substances the minority carriers are

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Holes

Electrons

Neutrons

None

The least count of stop watch is 0.10 sec,The time of 20 vibrations of pendulum is 40 sec The maximum possible percentage uncertainly in time period is

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0.016

0.10

0.001

0.005

The principle of D.C. motor is

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Force experienced by a conductor in electric field

Force experienced by a conductor in a magnetic field

Force experienced by a conductor in electric and magnetic field

None of these

Charge on alpha particle is equal to the charge on the nucleus of

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Hydrogen

Helium

Lithium

Beryllium

The decay constantγof a radioactive sample

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Decreases as the age of atoms increase

Increases as the age of atoms increase

Is independent of the age

Depends on the nature of activity

The medium in which speed of light is the same in all directions is called

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non-homogeneous medium

homogeneous medium

both of them

empty medium

When an ideal gas undergoes isothermal expansion the pressure of the gas in the enclosure falls this is due to

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Decrease in change on momentum

Decrease in frequency of collision

Both a and b

Neither a decrease in frequency of collision nor due to charge in momentum per collision

Internal friction of a fluid is called

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Surface tension

Resistance

Viscosity

None of these

If one mole of an ideal gas is heated at constant volume then

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Q_p = C_v ΔT

W = C_v ΔT

Q = C_p ΔT

ΔU = C_v ΔT

Generator is a device which converts

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mechanical energy into electrical energy

kinetic energy into potential energy

chemical energy into mechanical energy

electrical energy into mechanical energy