Question # 1

. 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

What happens to the centripetal acceleration of a particle, when its speed is doubled and angular velocity is halved?

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halved

doubled

remain unchanged

becomes four times

Which of the following is a unit of energy?

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unit

whatt

Horse Power

None of the above

The relationship between Boltzmann constant K with R and N_Ais given as:

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k = RN_A

k = R/N_A

k = NR/N_A

None of these

A charge of 2C experiences a force 2000N in a uniform electric field. In this fieldthe potential difference between two points separated by a distance 1cm is

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2V

10V

5V

20V

The law of thermodynamics which discusses the condition under which heat energy is converted into and equivalent amount of work is:

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1st

2nd

3rd

None of these

The angle of projection, at which the range of projectile would become half of its maximum value.

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45Degree

30Degree

15Degree

60 Degree

A PN junction diode cannot be use:

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As rectifier

For converting light energy to electrical energy

For getting light radiation

For increasing the amplitude of an ac signal

The time of flight of a projectile is maximum when angle of projection is:

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30 Degree

45Degree

60Degree

90Degree

A stone of mass 0.5kg tied with a string of length 1m is moving in a horizontal circle with a speed of 4ms-1 . The tension acting on the string in newton is:

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2

0.2

8

0.8

In a full wave rectifier:

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DC current is twice that of half wave rectifier

DC pulses are twice per cycle that of half wave rectifier

DC voltage is twice that of half wave rectifier

All are correct

A pure semiconductor has:

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An infinite resistance at 0^oC)

A finite resistance which does not depend upon temperature

A finite resistance which decreases with temperature

A finite resistance which increase with temperature

Two wires of same material have lengths L and 2L and cross-sectional area 4A and A respectively. the ratio of their specific resistance would be:

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1: 1

1: 8

8: 1

1: 2

Photo cells is a device which convert light into:

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Wave nature

Particle nature

Particle wave nature

Dual nature

The energy of photon of energy 1 eV is:

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1240 nm

1040 nm

1000 nm

620 nm

The radius of orbit of a geostationary satellite depends upon:

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Mass of satellite and its time period

Mass of satellite and mass of earth

Mass of earth, mass of satellite and time period of satellite

Mass of earth and time period of earth

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 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 potential difference applied to an X-rays tube is increased. As a result, in the emitted radiation

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The intensity increases

The minimum wavelength decrease

The intensity remains unchanged

Both B & C

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

Temperature of black body radiating at 270c is increased to 327oc, then emittedenergywill increase by

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2 times

12 times

16 times

4 times

An electric motor exerts a force of 40 N on a cable and pulls it by a distance of 30 m in one minute. The power supplied by the motor in watts is

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20

200

2

10

For a normal AC cycle, during T/2 to T the diode act as:

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Open switch

full wave rectifier

Close switch

All are correct

If the tension in a string stretched between two fixed points is made four times, the frequency of the fundamental harmonic will become:

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Two times

Three times

Four times

Six times

A listener observes the frequency “f” of stationary source. If it move toward with 3 times of velocity of sound. Then the apparent frequency of the sound will be

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f

3f

f/2

4f

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

If a source of emf is traversed from positive to negative the potential change will be:

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Positive

Negative

Zero

Constant

Truth of kinetic energy theory is confirmed by:

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Diffusion of gases

Brownian motion

Both A and B

None of these

In the theory of dimensional analysis, heat may be properly represented by:

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ML²T^-2

MT^-2

ML^-1T^-1

None of these

Figure represents a graph of kinetic energy (K) of the photoelectrons (in eV) and frequency (v) for a metal used as cathode in photoelectric experiment. The work function of metal is:

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1 eV

2 eV

1.5 eV

3 eV

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

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

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

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6V

60V

6000V

600V

An engine pumps out 40 kg of water in one second. The water comes out vertically upwards with a velocity of 3ms-1 . What is the power of engine in kilowatt?

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1.2kW

120kW

12kW

1200kW

According to Bohr’s theory, a line in the Ballmer series arises when the electron jumps from any of the higher orbits to the orbit with quantum number:

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1

2

3

4

Pressure may be defined as_____per second per unit area:

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Change in force

Change in momentum

Change in energy

Work done

When the length and area of cross-section both are doubled, then its resistance:

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Will become half

Will remain the same

Will be doubled

Will become four times

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

A device which convert DC into AC is calleD)

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Invertor

Generator

Rectifier

Motor

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

As in linear motion force determines linear acceleration where as in circular motion torque determines its

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Angular acceleration

Linear acceleration

Vibratory acceleration

Tangential acceleration