Online Test

Question # 1

Since density is proportional to the pressure, so the speed of sound by the variation in the pressure of the gas is

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Affected

Not affected

Slightly affected

None of these

The speed of sound at 30°C is approximately

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332 m/s

335 m/s

340 m/s

350 m/s

The ratio of total energy of a harmonic osillator to its average energy with respect to position will be

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1 : 2

3 : 1

1 : 3

2 : 11

The population inversion in He - Ne laser is achieved by

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Light of high frequency

Heating the system

Direct coliseums

None of these

Electromagnetic waves emitted by hot bodies are called:

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Photoelectrons

Alpha rats

Thermal radiation

None of these

The critical temperature Tc for Aluminium is

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2.1 K

1.1 K

1.18 K

1.19 K

What is the angle between electric field and equi-potential surface

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90°

0°

0° to 90°

0° to 180°

If we take initial phase as π/2 or 90^o, the displacement is

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X = X_o cos (ωt + 90^o)

X + X_o sin (ωt + 90^o)

X = X_o cos ωt

None of these

As 1 ohm x 1 farad = 1 second For MΩ x PF =

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Second

ms

μ s

Ms

Spectrometer using diffraction grating can measure

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Wavelength of light

Frequency of light

Intensity of light

None of these

A person standing on a rotating platform has his hands lowered.He suddenly outstretches his arms.The angular momentum

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Becomes zero

Increases

Decreases

Remains the same

α-particle is absorbed by

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1 mm sheet of copper

A paper

Lead sheet of 1 cm

None of these

The element used for radioactive Carbon dating for more than 5600 years life of the isotope is

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15 minutes

30 minutes

45 minutes

1 hour

The resistance of ideal voltmeter is

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Zero

Infinite

Very small but not zero

Equal to resistance of galvanometer

Speed of light in vacuum depends upon:

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Frequency

Wavelength

Amplitude

None of above

The unit of thermodynamic scale is

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C^o

K

F^o

All of these

In inverting amplifier if there is no potential difference between inverting and non-inverting inputs they V_o=

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V_cc

-V_CC

Zero

Infinite

When NPN transistor is used as an amplifier

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Electrons move from base to emitter

Electrons move from emitter to base

Electrons move from collector to base

Holes move from base to emitter

Mercury thermometer can be used to measure temperature up to

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260°C

100°C

360°C

450°C

A man pushes a wall and fails to displace it. He does

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Negative work

Positive work but not maximum work

No work at all

Maximum positive work

Each atom in a metal crystal vibrates about a fixed point with a amplitude that:

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Decreases with rise in temperature

Is not affected by rise in temperature

Increases with rise in temperature

Both B and C

None of these

Any superconductor with critical temperature above 77 K, is referred as

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low temperature superconductor

high temperature superconductor

very low temperature superconductor

none of them

Velocity of sound in vacuum (in m/s) is

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330

1000

156

0

The equations of pair production is

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hf = 2 m_oc² - KE(e^-) + K.E (e⁺)

hf = 2 m_oc² + KE(e^-) + K.E (e⁺)

hf = 2 m_o²c² + KE(e^-) + K.E (e⁺)

hf = 2 m_o²c + KE(e^-) + K.E(e⁺)

The angular momentum of a system of particles is not conserved

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When net external force is acting upon the system

When a net external torque is acting upon the system

When a net external impulse is acting upon the system

None of these

The elementary particles are

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Photons

Leptons

Hadrons

A and B

In an electric generator an induced emf is also generated when

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Coil has constant area

Constant magnetic field

Constant frequency

All of them

The length of the standard metre measured by Michelsion's interferometer comes out to be

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1,553, 163.5 wavelength

1553.5 wavelength

155316.5 wavelength

none of them

The direction of a vector in a space is specified by

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One angle

Two angles

Three angles

Cannot be specified

When the observer is moving away from the source, the observed frequency

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remains the same

increases

decreases

none of them

The wave of generated in spring are also called

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Sound waves

Compressional waves

Mechanical waves

None of these

Spectrometer can be used to

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Measure wave length of light

Measure refractive index of the materials

Study spectra of light

All

SI unit of current describes the flow of charge at the rate of:

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One ampere per second

One coulomb per second

One electron per second

6.25 X 10¹⁸electrons per second

Both B and D

A driven harmonic oscillator is the device in which, a physical system undergoes

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Free vibrations

Forced vibrations

Powerful vibrations

None of these

Radio frequency (R.F.) shielding of a coil means to protect from external circuit

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Varying magnetic field

Magnetic field

Dust and heat

Electric field

A wire is stretched to double of its length.The strain is

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2

1

Zero

0.5

The light pulse form a helium-neon laser is

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monochromatic

coherent

intense

all of them

What is the ratio of r.m.s velocity for O₂ to H₂?

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1/4

4

√4 : 1

1 : √4

When current is passed through a wire, heat is produced due to

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Inter atomic collision

Inter electron collision

Collision of conduction electrons with atom

None of these

Theα-particle ionizes the particles in its way and adopt the path which is

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Curved

Straight

Zig-Zag

None of these

A rheostat can be used as

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potential divider

thermistor

current divider

none of them