Question # 1

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

In an 𝑎 −decay:

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The parent and daughter nuclei have same number of protons

The daughter nucleus has one proton more than parent nucleus

The daughter nucleus has two protons less than parent nucleus

The daughter nucleus has two neutrons more than parent nucleus

A church organ consist of open ended pipes ranging from 4m to 4 mm, if the speed ofsound is considered as 400 m/s then the min and max frequency is:

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400 Hz and 4 kHz

100 Hz and 100 kHz

50 Hz and 50kHz

400 Hz and 400 kHz

Compton Effect makes the use of the law of conservation of:

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Energy

Momentum

Charge

Both (a) & (b)

Carnot cycle is:

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Reversible

Irreversible

Sometimes A, Sometimes B

None of these

What will be efficiency of carnot engine when it is operated between the temperatures 47^oC and 127 ^oC:

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Reversible

Irreversible

Sometimes A and B

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

A point on the rim of a wheel 4m in diameter has a velocity of 1600 cm s-1. The angular velocity of the wheel is

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2 rad s^-1

4 rad s^-1

6 rad s^-1

8 rad s^-1

During a negative β-decayv

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An atomic electron is ejected

A neutron in the nucleus decays emitting an electron

An electron which already present within the nucleus is ejected

A part of binding energy of nuclei is converted into electron

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

The equation W = ________𝜟U represents:

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Thermal process

adiabatic process

Isobaric process

None of these

How many photons per second does a one-watt bulb emit if its efficiency is 10% and the wavelength of light is 500 nm:

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2.53 × 1017

2.53 × 1019

7.5 × 1019

7.5 × 1017

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

In photoelectric effect, electrons are emitted:

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Slowly

Intermittently

Both (a) & (b)

Instantly

The direction of angular velocity is along

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Tangent to the circle

Axis of rotation

Inward the radius

Out ward of the radius

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

A radioactive isotope 𝟐𝟑𝟖 𝑼 decays consecutively to 𝟐𝟑𝟒 𝑼 the particles emitted are:

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One 𝛼 and one 𝛽

Two 𝛼 and one 𝛽

e 𝛼 and two 𝛽

Two 𝛼 and two 𝛽

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

The power needed to lift amass of 5000g to height of 1min 2 second is

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2.45 watt

24.5 watt

245 watt

2.45 k watt

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

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Continuous wave

Longitudinal wave

Pulse

Transverse wave

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

Diesel engine coverts ____________ of available heat energy into work.

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20% to 25%

25% to 30%

30% to 35%

35% to 40%

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

A stone attached to one end of a string is revolved around a stick so that the string winds on the stick and gets shortened) What is conserved)

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angular momentum

kinetic energy

linear momentum

none of the above

Thermal radiations are a type of:

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Mechanical waves

Electromagnetic waves

Alpha rays

Electrons

The phenomenon of radioactivity is associated with:

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Fission of nucleus

Disintegration of neutrons

Emission of spectral lines

Spontaneous disintegration of the nuclei of atoms

A human eye can detect the electromagnetic radiations of the type:

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Infrared radiations

For- infrared radiations

X-rays radiations

Red radiations

The frequency of the fundamental mode of open at one organ pipe is 400 Hz. Ifone end of pipe is closed the fundamental frequency will be

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800 Hz

600 Hz

400 Hz

200 Hz

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

The mud flies off the tyre of a fast moving car in the direction

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parallel to the moving tyre

anti parallel to the moving tyre

tangent to the moving tyre

none of these

Interference and diffraction confirm:

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Particle nature

Wave nature

Dual nature

None of these

If a transverse wave has a speed of 10 m/ sec and frequency of 10 cycle/ sec itswavelength is:

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1 m

10^-2 cm

10 m

10 cm

A ball is thrown vertically upwards. Neglecting air resistance, which statement is correct?

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The kinetic energy of the ball is greatest at the greatest height attained

The potential energy of the ball increase uniformly with time during the ascent

By the principle of conservation of momentum. The momentum of the ball is constant throughout its motion

By the principle of conservation of energy, the total energy of the ball is constant throughout its motion

When a person lifts a body from ground work done by lifting force is?

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Positive

Negative

Zero

Half of positive maximum

The energy of photon of wavelength 620 nm is:

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0.5 eV

1.0 eV

1.5 eV

2.0 eV

Where in standing wave, do the vibrations of the medium occur?

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Only at the nodes

Only at the antinodes

At all points between the nodes

At all points between the antinodes

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

Interference and diffraction of light confirms its:

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Particle nature

Dual nature

Wave nature

Electromagnetic nature

Electromagnetic waves emitted by hot bodies are called:

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Photoelectrons

Alpha rats

Thermal radiation

None of these

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

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Linear velocity

Acceleration

Speed

All of these

The simplest type of rectification known as half wave rectification is obtained by

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Using a transistor

Suppressing the harmonics in A.C. voltage

Suppressing half wave of A.C. supply by using diode

Using a Coolidge