Question # 1

If P is the pressure and V is the volume, Then PV will represent:

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Power

Work

Force

None of these

What will be the number of photons emitted per second by 25 W source of monochromatic light of wavelength 600 nm:

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7.5 × 1017

7.5 × 1019

5.5 × 1019

5.5 × 1017

When a dielectric is inserted between the plates of a capacitor, Which one is true

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Energy stored increase

Energy stored decrease

Capacitance decrease

All

In a one-dimensional elastic collision, the relative velocity of approach before collision is equal to:

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Sum of the velocities of the bodies

e times the relative velocity of separation after collision

1⁄𝑒 times the relative velocity of separation after collision

relative velocity of separation after collision

Continuous spectrum of X-rays id due to an effect known as

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Photoelectric effect

Compton effect

Heisenberg effect

Bremsstrahlung

A positively charged particle is moving perpendicular to a uniform magnetic field. The magnetic force makes the particle to move along:

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An elliptical path

A circular path

A parabolic path

None of these

The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the Stopping distance will be:

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The same

Doubled

Halved

Four times

A gas which strictly obeys the gas laws under all conditions of temperatures and pressure is called:

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Ideal gas

Inert gas

Real gas

None of these

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

The spectrum of a star’s light is measured and the wavelength of one of the lines as thesodium’s line is found to be 589 nm. The same line has the wavelength of 497 nm whenobserved in the laboratory. This means the star is

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Moving away from the earth

Moving towards the earth

Stationary

Revolving around the planet

The magnetic field of a solenoid is quite similar to that of a:

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Straight conductor

A horse shoe magne

Any magnet

A bar magnet

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

The activity of a radioactive sample is 1.6 curie and half-life is 2.5 days. Its activity after 10 days will be:

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0.8 Curie

0.1Curie

0.4 Curie

0.16 Curie

In closed end organ pipe, the frequency of first harmonic is 300 Hz. The frequency ofthird overtone is :

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900 Hz

1500 Hz

2100 Hz

600 Hz

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

. 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

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

Photo cells are used for :

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Security and counting system

Automatic door system

Automatic street lighting

All of these

In photoelectric effect experiment, stopping potential depend upon

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Intensity of light

Frequency of light

Photoelectric current

Both A and B

Carnot cycle is:

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Reversible

Irreversible

Sometimes A, Sometimes B

None of these

Beta particles have penetration of about:

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100 times more than that of the gamma particles

100 times less than that of an alpha ray

100 times more than that of an alpha ray

10 times more than that of an alpha particle

Nuclear fission experiments show that the neutrons the uranium nuclei into two fragment of about the same size. This process is accompanied by the emission of several:

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Protons and positrons

𝛼 −partilces

neutrons

Protons and 𝛼 −partilces

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

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

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

A cell of negligible resistance and e.m.f 2 V is connected across a series combination of 2,3 and 5 ohms. The p.d. across the 3 Ω resistor is

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0.6 V

1/3 V

2/3 V

4/3 V

The unit Compton wavelength is same as:

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Compton wavelength

Compton frequency

Compton shift

Both (a) & (b)

The energy of photon of energy 1 eV is:

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1240 nm

1040 nm

1000 nm

620 nm

electrons from the surface of a metal when:

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It is heated to a high temperature

Radiation of suitable wavelength falls on it

Electrons of suitable velocity strike it

It is placed in a strong electric field

A process which is carried at constant temperature and Boyle's law can be applied is called:

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Adiabatic process

Isothermal process

Isochoric process

None of these

The number of electrons in a nucleus X of atomic number Z and mass number A is:

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A

W

Z

Y

In Compton effect, it was considered that X-rays consist of:

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Electrons

Positrons

Photons

All of these

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

Geo stationary satellite remains

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Stationary

Both "A" & "B"

Appear

None of them

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

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30 Degree

45Degree

60Degree

90Degree

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

If the K.E. of a body is increased by 300%, its momentum will increase by:

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100 %

150 %

√300%

175 %

The ratio of the SI unit to the C)G.S unit of torque is.

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10⁷

10⁹

10⁰

10³

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

A body is in translational equilibrium if

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P = 0

L = 0

F = 0

 = 0

An electric field can deflect:

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X-rays

Neutrons

𝛼 −particles

𝛾 −rays