Online Test

Question # 1

A bomb of mass 9 kg explodes into two pieces of mass 3 kg and 6 kg.The velocity of mass 3 kg is16 ms^-1,K.E of mass 6 kg is

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96 j

192 j

384 j

768 j

An automobile moves with constant speed along a circle of radius 40 m. It takes 2 μ second to complete one circle,The average speed for one complete circle is

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20 ms^-1

40 ms^-1

60 ms^-1

0 ms^-1

The direction of Lorentz force depends on the sign of change in a magnetic field

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Negative

Positive

No charge

Both positive and negative

The frequency of the incident light falling on a photosensitive metal plate is doubled the kinetic energy of the emitted photoelectrons is

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Double the earlier value

Unchanged

More than doubled

Less than doubled

Even the small viscosity of the air causes a retarding force on car at high speed is

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Small

Large

Very large

None of these

The valence band of an atom in a solid

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is always empty

may or may not be empty

can never be empty

none of them

An alternating current is converted into direct current by a

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dynamo

rectifier

transformer

motor

Which one of the following is not a mode of radioactivity decay

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Electron Emission

Alpha Emission

Proton Emission

Gamma Emission

Viscosity of plasma at 30^oC in Nsm^-2

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1.6 × 10^-3

1.595 × 10^-3

1.67 × 10^-3

1.69 × 10^-3

The kinetic energy of electron (in electron volt),moving with the velocity of 4 x 10⁶ m/s will be

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30 eV

45 eV

50 eV

60 eV

Radioactive element are those which have atomic number

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Great than 92

Greater than 83

Greater than 82

Less than 82

Which property of waves proves that light is a transverse wave?

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diffraction

interference

polarization

reflection

Isotopes have same number of:

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Protons

Neutrons

Nucleons

Photons

When a dielectric material is introduced between the plates of a charged condenser the electric field between the plates

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Decreases

Increases

No change

May increase or decrease

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 polarized can be achieved by using process like

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Coherent sources

Diffraction

Selective absorption

None of these

A thermister is a

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Heat temperature resistor

Current sensitive resistor

Voltage sensitive resistor

None of these

The increase in the speed of sound per degree Celsius rise in temperature is approximately

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61 m/s^-1

6.1 m/s^-1

0.61 m/s^-1

0.061 m/s^-1

A converging lens in used to from an image on a screen when the upper half of the lens is covered by an opaque screen

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Half the image will disappear

No change either in size or in intersity

Intensity of image will increase

Intensity of the image will decrease

A thin layer of oil on the surface of water looks colored due to:

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Diffraction of light

Reflection of light

Dispersion of light

Interference effect of light

What determines half-life of a radioactive element?

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Atomic number

Mass number

Temperature

None of these

The terminal velocity of for a water droplet of radius 10^-5 m is of the order of

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1 cm/s

1 mm/s

1 nm/s

1 μm/s

As the solid state detector absorbs so less energy of the incident particle and junction become front surface. So it called the detector as

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Surface contact

Surface barrier

Surface dependent

None of these

X-rays cause damage to

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Cancerous cells

Living tissues

Health cells

None of these

The pipe has a length of 1m. Determine the fundamental frequency when one end of the pipe of closed. Speed of air is 340 ms^-1

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80 Hz

82 Hz

84 Hz

85 Hz

Mathematical expression for Kirchhoff's 1st rule is

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∑R = 0

∑V = 0

∑I = 0

∑IR = 0

S,I unit of magnetic flux is

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Weber metre^-2

Weber

Weber per metre

Weber per metre⁴

Ordinary light has components of vibration in

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One direction

Different direction

All directions

None of these

CRO is used to find

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Phase difference between A-C voltages

Frequency and Time period of A-C voltages

Peak and rms value of alternating voltage

All of these

The currents and voltages in A.C. circuits are controlled by

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Resistor

Capacitor

Inductor

All of them

An inductor is a solenoid having the self inductance which is

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Small

Large

Medium

None of these

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12 cm / sec

6 m / sec

3 cm / sec

24 cm / sec

In the same medium, velocity of the wave:

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Goes on increasing

Remains constant

Goes on decreasing

None of these

In AND gate output is 0 if:

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All inputs are 1

At least one input is 1

At least one input is 0

All inputs are 0

After absorbing so many electrons, it becomes

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Stable

Unstable

Radioactive

None of these

The Ultrasonics have the frequencies:

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In audible range

Above 20,000 Hz

Below 20Hz

None of these

The atoms molecules or ions in a crystalline solids are at room temperature

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Motionless

Vibrate violently

Fixed

Simply vibrate

The emission of electrons from a metal surface when exposed to light of suitable frequency is called the

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pair production

Compton effect

photoelectric effect

relativity

Pico is the prefix for

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10^-10

10^-12

10^-15

10^-18

'γ' is the ratio for monoatomic gas is

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1.72

1.67

1.63

1.60

Gamma-rays are electromagnetic radiations similar to

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Radio waves

Photons

X-rays

Beta rays