Question # 1

In 420 days, the activity of a sample of polonium (Po) fell to one-eight of its initial value. The half-life of polonium is :

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140days

45days

87days

90days

A body of mass m tied to a string is moved in a vertical circle of radius r. the difference in tensions at the lowest point and the highest point is.

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2 mg

4 mg

6 𝑚g

8 mg

Two artificial satellites of unequal masses are revolving in a circular orbit around the earth with a constant speed. Their time periods:

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Will be different

Will depend on their masses

Will be same

Will depend upon the place of their projection

If C_vdonotes molar specific heat at constant volume and𝜟 T is the change in temperature, then C_v𝜟T gives:

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Volume

Pressure

Energy

Entropy

If the range of a projectile is R, the potential energy will be maximum after the projectile has covered (from start) distance equal to:

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R/2

R/4

R

R/9

Ratio of dimension of K.E and power is:

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1:1

T:1

1:T

M:J

A wave which consists of a single, non-repetitive disturbance is called a

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Continuous wave

Longitudinal wave

Pulse

Transverse wave

An organ pipe open at both ends and another organ pipe, closed at one end willresonate with each other, if their lengths are in ration of

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1:1

1:4

2:1

1:2

When the radioactive nucleus emits a beta particle, the proton neutron ration:

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increases by one

Remains same

Decreases by one

Decreases by four

A closed organ pipe and an open organ pipe have their first overtone identical infrequency. Their lengths are in ratio

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3:4

1:2

2:3

3:5

Two railway trucks of masses m and 3m move towards each other in opposite directions with speeds 2v and v respectively. These trucks collide and stick together. What is the speed of the trucks after the collision?

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v/4

v/2

v

5v/4

The specific resistance of a wire varies with its:

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Length

Cross-section

Mass

Material

A motor boat is travelling with a speed of 3.0 m/sec. If the force on it due to water flow is 500 N, the power of the boat is

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150 KW

1.5 KW

heat energy

chemical energy

A particular wavelength received from a galaxy is measured on earth and isfound to be 5% more than that its wave length on earth. Hence galaxy is

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Moving towards earth

Going away from earth

Stationary with respect to earth

None

Two astronauts in a satellite must have

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Same masses

Same real weights

Same apparent weights

None of these

The nature of thermal radiation is similar to:

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Ultraviolet rays

Light rays

Both of them

None of them

A body is in translational equilibrium if

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P = 0

L = 0

F = 0

 = 0

Swimming is possible on account of

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1^st law of motion

2^nd law of motion

3^rd law of motion

Newton’s law of Gravitation

An electron in the n=1 orbit hydrogen atom is bound by 13.6 eV. If a hydrogen atom is in the n=3 state, how much energy is required to ionize it:

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13.6 eV

4.53 eV

3.4 eV

1.51eV

Beta particles have less ionizing power than that of alpha particles because:

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Their smaller energy

Their smaller mass

Their smaller density

Their smaller charge

The momentum of a particle is numerically equal to its K.E. What is the velocity of a particle?

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9 ms^-1

3 ms^-1

2 ms-1

1 ms^-1

The maximum kinetic energy of emitted photoelectrons depends upon:

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The intensity of incident light

Frequency of the incident light

Temperature of the surface

All of above

. A force "F1" acts on a body through distance "S1" in the direction of motion and does work "W1". Similarly another force "F2" act on same body through distance "S2" but in opposite to the direction of motion and does work "W2". Now if F1 = F2 and S1 = S2 then which statement is correct.

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W1 = W2

W2< W2

W1 > W2

W1 = W2= 0

For atomic nucleus, the binding energy per nucleon with increase in mass number:

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Increases continuously

Remains same

Decrease continuously

First increases and then decreases with increase in mass number

A longitudinal sinusoidal wave has wavelength of 1cm and a period of 2sec. Its wavevelocity is:

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50 cm/ sec

0.5 cm/ sec

5 m/ s

0.005 m/ sec

Which one is the case when the wavelength is actually changed?

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When source move relative to observer

When observer move relative to source

When observer moves around a stationary source at the center of circle

When the relative displacement between source and observer is zero

De-Broglie received the Nobel prize in

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1929

1937

1928

1924

The maximum kinetic energy of emitted photoelectrons depends upon:

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The intensity of incident light

Frequency of incident light

Metal surface

Both frequency of incident light and metal surface

If a rotating body is moving counter clockwise, direction of angular velocity will be

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along linear velocity

towards the center

along the axis of rotation

away from center

A certain engine coverts 20% of available heat energy into work. Then its efficiency will be:

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20%

80%

50%

None of these

Which of the following does not have the same units:

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Work

Heat

Kinetic energy

Power

When two semiconductors of p- and n-type are brought into contact, they from a p-n junction which act like a:

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Conductor

Amplifier

Oscillator

Rectifier

Capacitor stores energy in the form of :

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Electric field

Both of these

Magnetic field

Gravitational field

When temperature increases, frequency of organ pipe:

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Decreases

Remains the same

Increases

Becomes zero

A non-inverting amplifier has infinite input resistance then the voltage gain of noninverting amplifier will be:

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Zero

Infinite

One

100

The motion of molecules in gases i:

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Orderly

Random

Circular

All of these

A piece of Aluminium (Al) and a piece of Germanium (Ge) are cooled T1 K to T2 K. The resistance of:

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Each of them increases

Each of them decreases

Al increases and Ge decreases

Al decreases and that of Ge increases

Newton’s third law concerns the forces of interaction between two bodies. Which of the following statement relating to the third law is not correct:

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The two forces must be the same type

The two forces must act on different bodies

The two forces are always opposite in direction

The two forces are equal and opposite so the bodies are in equilibrium

A non-conducting semiconductor diode is:

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Forward biased

Poorly biased

Reverse biased

None of them

The ideal gas obey gas law at:

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Low tempratures and high pressures

High temperatures and low pressures

All temperatures and pressures

None of these

The ratio of output work per cycle to input energy per cycle is called:

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Entropy

Internal energy

Efficiency

None of these