Online Test

Question # 1

A body falls freely from rest.It covers as much distance in the last second of its motion as covered in the first three seconds.The body has fallen for a time of

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3 s

5 s

7 s

9 s

When the vectors are mutually perpendicular then the product is

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Maximum

Minimum

Zero

None of these

Gamma radiations are emitted due to:

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De-excitation of atom

De-excitation of nucleus

Excitation of atom

Excitation of nucleus

How much water a pump of 2kW can raise in one minute to a height of 10 m.take g = 10 m/s²?

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1000 liters

1200 liters

100 liters

2000 litre

A phenomenon in which a high energy photon scattered by an atomic electron and transfer a part of its energy is known as

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Photoelectric effect

Compton effect

X-rays

None of these

The function of compensator plate in interferometer is to

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Interfere properly

To equalize the distance of M₁ and M₂

Reflecting light properly

None of these

Which of the following is not dependent on the intensity of incident radiation in a photoelectric experiment?

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Work function of the surface

Amount of photoelectric current

Stopping potential will be reduced

Maximum K.E of photoelectron

Which one of the following is correct?

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moderators slow down the neutrons

moderates absorb the fast neutrons

moderators reflect the fast neutrons

moderators bring the neutrons to rest

Consider a photon of continuous X-rays and a photon of characteristic X-ray of same wavelength. Which of the following is/are different for the two photons

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Frequency

Penetrating power

Energy

Method of production

A tank containing water has an orifice in one vertical side. If the centre of the orifice is 10 m below the surface level in tank, then velocity of efflux is

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44 ms^-1

14 ms^-1

10 ms^-1

49 ms^-1

With the rise of temperature, the drift velocity of free electrons

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Increases

Decreases

Remains constant

None of these

Working of a galvanometer depends on

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Force exerted on a coil

Torque on a coil

Induced emf

None of these

A particle executes SHM with a time period of 2 s and amplitude 5 cm Maximum magnitude of its velocity is

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10 π cms^-1

20 π cms^-1

2.5 π ms^-1

5 π cms^-1

If the line of action of force passes through the pivot point then the torque produced will be

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maximum

zero

minimum

none of them

The blood pressure of man

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Increase with age

Decrease with age

Remains same

Cannot predicted

Which of the following has no dimension

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Stress

Strain

Elastic modulus

Both strain and elastic modulus

Which one of the following phenomena is not explained by Huygen's construction of wavefront?

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Refraction

Reflection

Diffraction

Origin of spectra

The military applications of Doppler's effect are

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Location of submarines

Control of anti submarine weapons

Depth measurement of sea

All of these

A charge of 10 C is moved along an equipotential surface having a potential of 2V. The work done is

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10 j

Zero

2 j

20 j

Which one is ferromagnetic

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Ferries

Cobalt

Nickel

All

A unit set is the smallest basic structure which is:

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One dimensional

Two dimensional

Three dimensional

Four dimensional

None of these

At any instant the ratio of the amount of radioactive substance is 2 : 1 their half lives be respectively 12 and 16 hours,then after two days what will be the ratio of the substances?

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1 : 1

2 : 1

1 : 2

1 : 4

The emf is the "cause" and potential difference is its

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Result

Relation

Effect

None of these

Wheatstone bridge have number of resistance

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3

6

4

5

If a V, 90 W bulb is to be worked in 120 V line the resistance to be connected in series with bulb is

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20 Ω

10 Ω

40 Ω

30 Ω

The control rods in the atomic reactor helps to absorb the fast neutrons are

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Boron

Cadmium

Lead

All of these

The motion of a charged nucleus also produces a magnetic field which is

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Weaker than orbital electrons

Stronger than orbital electrons

Equal than orbital electrons

None of these

The critical temperature for mercury is

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1.18 K

4.2 K

3.72 K

7.2 K

The velocity of sound at t°C is given by the relation

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V_t= V₀+ 0.61 t

V_t= V₀+ 61 t

V₀= V_t+ 6 t

None of these

According to Maxwell's hypothesis a changing electric field gives rise to

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An e.m.f

Electric current

Magnetic field

Pressure radiant

An electron of mass 1.67 × 10^-31 kg moving with a speed of 1 × 106ms^-1 generates a wavelength of

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7 × 10^-10 ms^-1

5 × 10^-8 ms^-1

9 × 10^-6 ms^-1

None of these

Neutron produce ionization by knocking out proton which is

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Direct ionization

Indirect ionization

Both

None of these

What determines the hardness of the X-rays obtained from the x-rays tube?

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Current in the filament

Presence of air in the tube

Natural of target

Potential difference between the cathode and the target

SI unit of work is

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N-m

N-m²

N-ms^-1

N-ms^-2

How does a speed v of sound in air depend on atmospheric pressure

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v is independent of P

v∝P^1/2

v∝P²

v∝P

An object is placed at a distance 18 cm from a convex lens. The image is formed at a distance of 9 cm the focal length of the lens is

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6 cm

9 cm

10 cm

18 cm

The relation for the diffraction pattern, when it is minimum

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d/2 sin θ = λ

sin θ = λ/2

d sin θ = λ

None of these

The approximate efficiency of fossil fuel power plants is

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20 - 27%

30 - 40%

40 - 50 %

40 - 42%

You are traveling in a car during a thunder storm. In order to protect yourself from lightning you would prefer to

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Remain in car

Take shelter under tree

Get on and lie flat on the ground

Touch the nearest electric pole

Black colour is:

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A good absorber of heat

A bad absorber of heat

A good reflecter of heat

Both (A) and (C)

Both (A) and (B)

Moment of inertia depends on mass and also on

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r

r²

r³

None of these