Question # 1

Minimum energy needed to escape an electron ofrm metal surface is called:

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Threshold energy

Threshold frequency

Work function

Work ability

The value of Wien's constant:

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2.9x10^-3mk

2.19x10^-7mk

3.18 x10⁶ km^-1

6.21 x 10^-9m²wk³

Anti particle of electron is

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Proton

Photon

Neutron

Positron

Compton shift is maximum for scattering angle of photon

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0^o

90^o

180^o

45^o

When platinum is it becomes orange at.

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500^oC

900^oC

1100^oC

1300^oC

Einstein was awarded Nobel prize in physics in

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1905

1911

1918

1921

The materialization of energy take place in the process of.

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Photo electric effect

Compton Effect

Pair production

Annihilationof matter

Internal frame is a frame is which

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1st law holds

2nd law holds

3rd law holds

Kelvin's law holds

Pair production occurs only when energy of photon is at least equal in:

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1.02keV

1.02 eV

1.02 MeV

1.02 GeV

Platinum wire becomes yellow at a temperature of.

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900^oC

1300^oC

1600^oC

500^oC

The value of Stefan is constant is:

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4.57 x 10^-8 m²k²

5.67 x10^-8 wm^-2k^-4

6.67x 10^-11 wm²k⁴

7.45 x 10^-9 m² wk³

The wavelength associated with the protons moving at speed of 40 m/s is.

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7.20 nm

9.02

15.7 nm

17.3 nm

The stopping potential for a certain metal is 10 volts. Thus work function for the cathode is.

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10 J

1.6 X 10^-18 J

1.6 X 10^-19 J

1.6 X 10³⁰ J

Photo electrons are emitted y using visible light when the metal is.

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sodium

Copper

Nicked

Cobalt

Potassium Cathodes in photocell emit electrons for a light.

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Visible

Infra red

Ultra violet

X rays

The dimensions of Plank's constant is same as that of.

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Energy

Power

Acceleration

Angular momentum

Pair production can take place only when energy of radiation is equal and greater than 1.02 MeV, thus correct option is.

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X rays

Gama rays

Heat Radiation

Ultraviolet rays

If the kinetic energy of a free electron doubles, its de Broglie wavelength changes by the factor.

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√2

1/√2

2

1/2

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