Question # 1

Truth of kinetic energy theory is confirmed by:

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Diffusion of gases

Brownian motion

Both A and B

None of these

A total charge of 100C flows through 12W bulb in a time of 50 second. Which is the potential difference across the bulb during this time?

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0.12V

6.0V

2.0V

24V

In a half wave rectifier circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be:

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25 Hz

70.7 Hz

50 Hz

100 Hz

A particle is moving with constant speed by keeping itself at constant distance from a fixed point in a given plane. Its motion is

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Circular motion

Uniform circular motion

Uniform circular motion with fixed axis of rotation

Uniform circular motion with axis of rotation not defined

A rigid uniform bar of length 2.4 m is pivoted horizontally at its mid-point, weights are hung from two points of the bar as shown in diagram. To maintain horizontal equilibrium, a couple is applied to the bar: What is the torque and the direction of couple?

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40 N m clockwise

40 N m anti-clockwise

80 N m clockwise

80 N m anti-clockwise

The binding energy per nucleon is:

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Greater for heavy nuclei

Least for heavy nuclei

Greatest for light nuclei

Greatest for medium nuclei

A body crosses the topmost point of a vertical circle with critical speed. Itscentripetal acceleration, when the string is horizontal will be

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4g

3g

g

6g

A person holds a bucket of weight 60N. He walks 7 m along the horizontal path and then climbs up a vertical distance of 5 m. The work done by the man is:

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300 N-m

420 N-m

720 N-m

none of these

The ratio of the longest and shortest wavelength of the Lyman series is approximately:

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4/3

9/4

9/5

16/7

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

Intensity of light from a point source at the edge of unit sphere will be:

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𝑃

P(4π)

4𝜋

Bats navigate and find food by:

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Ultrasonic

Echolocation

Refraction

A 50 kg man with 20 kg load on his head climbs up 20 steps of 0.25 m height each. The work done in climbing is

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5 J

350 J

100 J

3430 J

Two bodies are projected at angles  and (90°–) with the horizontal at the same speed.The ratio of their maximum heights is

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1 : 1

1 : tan 

tan² : 1

A person weighing 20 mg walks on a level platform with a speed of 2 ms-1 . The work by the person against the force of gravity is:

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Zero

2J

60J

600J

When a particle moves in a circle the angle between it linear velocity and the angular velocity is always

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0°

180°

90°

none of them

A 4 m long string fixed at its ends resonate in 4 segments. The wavelength of the waveis:

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4m

0.5m

2m

0.25 m

The time period of revolution of geostationary satellite is

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1440 minutes

24 minutes

84 minutes

none of these

In electron microscope, we use high speed electrons because them

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Penetration power is higher

Wavelength is smaller

Frequency is smaller

K.E is smaller

The force which can do no work on the body on which it acts:

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Frictional force

Elastic force

Gravitational force

Centripetal force

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 body of mass m kg is lifted by a man to a height of one meter in 30 sec. Another man lifts the same mass to the same height in 60 sec. The work done by them are in the ratio

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1: 2

1: 1

2: 1

4: 1

You lift a suit case from the floor and keep it on a table. The work done by you on the suitcase does not depend on

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the path taken by the suitcase

weight of the suitcase

initial and final position

None

The value of universal gas constant R is:

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8.314 J/K mole K

8314 J/ mole K

8.314 J/ mole K

None of these

If an electron is accelerated such that its K.E is 4 times of its rest mass energythen thetotal relativistic energy of electrons is about

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5 × 10–12 J

4 × 10–13 J

3 × 10–13 J

6 × 10–12 J

Only those processes are probable to take place for which entropy os the system:

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Increases

Remains constant

Both A and B are correct

None of above

If the temperature difference between hot and cold body is greater the heat engine is:

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Not efficient

Less efficient

More efficient

NOne of above

Which of the following types of force can do no work on the particle on which it acts?

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Frictional force

Gravitational force

Elastic force

Centripetal force

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 certain noninverting amplifier has R1 of 1 kΩ and R2 of 100 kΩ. The closed-loop voltage gain is ………

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100,000

100

1000

101

No of spark plugs needed in diesel engine is:

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Four

Five

Six

None of these

Which one of the following statements regarding electrostatics is wrong?

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Charge is conserved

Charge is quantized

There is no field near an isolated charge at rest

A moving charge produces both electric and magnetic fields

The distance between the plates of a charged parallel plate capacitor is 4mm and potential difference is 6 volts. If the distance between the plates is increased to 12mm, then :

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The potential difference of the capacitor will become 18 volts

The P.D become 20 volts

The P.D will remain unchanged

The charge on condenser will reduce to one third

If velocity time graph is a straight line parallel to time axis then body is

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Moving with zero acceleration

Moving with constant velocity

Covering equal displacement in equal intervals of time

All of these

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

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6V

60V

6000V

600V

Carnot cycle is:

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Reversible

Irreversible

Sometimes A, Sometimes B

None of these

The magnitude of potential barrier for Ge is

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0.7 v

0.3 V

7v

3 v

Which of the Following bulb will glow Brightest?

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100W

200W

300W

400W

In uniform circular motion, the factor that remains constant is:

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Linear velocity

Acceleration

Speed

All of these

The power output of a full wave rectifier is:

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Equal to H.W.R

Twice of H.W.R

Half of H.W.R

Four times of H.W.R

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