Question # 1

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

The photoelectric effect was explained by:

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Einstein

Davison

Hertz

Planck

Geo stationary satellite remains

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Stationary

Both "A" & "B"

Appear

None of them

Torque is necessary for producing.

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angular speed

linear acceleration

angular acceleration

none of these

As the working substance of a heat engine completes a cycle, there is no change in:

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Internal energy

Pressure

Volume

All of these

Number of spark plugs needed in diesel engine is:

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Four

Five

Six

None of these

If the velocity of a body becomes half, the kinetic energy of body will become

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One fourth

Double

Four times

Half

When a radioactive nucleus remits a beta particle, the proton neutron ratio:

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Decreases

Increases

Remain same

None of the above

The time period of revolution of geostationary satellite is

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1440 minutes

24 minutes

84 minutes

none of these

A parallel plate air capacitor is charged and then isolated. When a dielectric material is inserted between the plates of the capacitor , then which of the following does not change:

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Electric field between the plates

Charge on the plates

Potential difference across the plate

Energy stored in the capacitor

On slightly disturbing a body which is an unstable equilibrium, its center of gravity

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rises

falls

remains constant

first rises then falls

Photo cells are used for :

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Security and counting system

Automatic door system

Automatic street lighting

All of these

Two projectiles ‘A’ and ‘B’ are thrown with same speed but at angle of 40 degree and 50 degree with the horizontal. The horizontal range of ‘A’ will be:

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Equal to that of ‘B’

Greater than that of ‘B’

Less than that of ‘B’

4/5times that of ‘B’

A sonar depth finder in a boat uses sound signals to determine the depth of water. Fourseconds after the sound leaves the boat it returns to the boat because of reflection fromthe bottom. Assume the speed of sound in water is 1,460 meters per second. The depth of the water is, in meters, :

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2,200

4,800

4,400

2,920

The stopping potential for a certain metal is 10 volt, the max. Energy of emitted electron is:

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10 J

100 J

1.6 × 10-18 J

1.6 × 10-19 J

In a photocell, certain metal emits electrons for :

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Visible light

Infrared light

Ultraviolet light

All of these

Two charges of equal magnitudes and at a distance r exert a force F on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is:

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F/8

F/4

F/16

4F

For a gas obeying Boyle's law, if the pressure is doubled the volume becomes:

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One half

Double

Four times

None of these

Of electron of 50 keV strike a heavy target. Then radiation emitted by target will be

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Visible light

Radio waves

Ultraviolet

None of these

In case of planets the necessary acceleration is provided by

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Gravitational force

coulomb force

frictional force

centripetal force

Change in momentum per second is:

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Product force and time

Product of pressure and area

Ratio of pressure and area

None of these

A circuit that converts Pulsating DC into smooth DC contain :

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Filter

Capacitor

Inductor

LC circuit

The specific resistance of a wire varies with its:

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Length

Cross-section

Mass

Material

An electric field can deflect:

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X-rays

Neutrons

𝛼 −particles

𝛾 −rays

Capacitance of a capacitor does not depend upon

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Separation between plates

Thickness of the plates

Area of the plates

Medium between the plates

A diode as a rectifier converts:

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A)c into D)c

D)c into A)c

Varying D)c current into constant D)c current

High voltage into low voltage and vice-versa

Half-life of radon gas is:

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1620 years

3.8 days

7 days

11 days

In photo electric cell, the photo electric current

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Decreases with increase in frequency of light

Depends on intensity and frequency of light

Does not depend upon the frequency of light and but depends upon intensity of light

Increases with increase in frequency of light

Carnot cycle is:

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Reversible

Irreversible

Sometimes A, Sometimes B

None of these

With the propagation of longitudinal waves through a material medium, the quantitiestransferred in the direction of propagation are:

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Energy, momentum and mass

Energy and momentum

Energy and mass

Energy

Two bodies moving towards each other collide and move away in opposite directions. There is some rise in temperature of bodies because a part of the kinetic energy is converted into

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heat energy

electrical energy

nuclear energy

mechanical energy

A process in which no heat enters or leaves the system is called.

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Adiabatic process

Isothermal process

Isochoric process

None of these

In uniform circular motion, the factor that remains constant is

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Linear velocity

Centripetal force

Acceleration

speed

Avogadro number is known as number of molecules in:

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One kg of a substance

Unit volume of a substance

One mole of a substance

None of these

Most motorbikes have ____________ cylinder/s engine but cars usually have _________ cylinders on the same crankshaft.

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Four , Six

One , four

two , five

None of these

The distance covered by a body in time ‘t’ starting from rest is:

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1/2 𝑡²

vt

𝑎𝑡²

𝑎𝑡₂

A stone is thrown upwards it returns to ground describing a parabolic path which of the following remains constant:

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Speed of the ball

Kinetic energy of the ball

Vertical component of velocity

) Horizontal component of velocity

The angular momentum changes form 2 units to 6 units in 4s. the torque is

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1 unit

3/2unit

1/2unit

4unit

The potential difference between head and tail of an "electric eel" can be upto.

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6V

60V

6000V

600V

Gain of operational amplifier is independent of;

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Internal structure

External Structure

Batteries

Potential changes

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