12th Class Physics MCQS Chapter 8

The value of Stefan is constant is:

4.57 x 10^-8 m²k²

6.67x 10^-11 wm²k⁴

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

7.45 x  10^-9 m² wk³

The most refined form of matter is:

Ice

Light

Smoke

Fog

The minimum energy required for occurrence of pair production is:

1.02Me.V

1.02keV

1.022eV

1.04MeV

An electron miroscope emplys which to one of the following particles?

All of the above

Electrons can be focused by a magnetic field

Electrons can be focused by an electric field

Electron ahve a wave nature

The numerical value of Compton wavelength is equal to

3.43 x 10^-12 m

1.43 x 10^-12m

2.43 x 10^-12m

0.43 x 10^-12m

The existence of positron was discovered in:

1928

1929

1933

1931

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

1?

2-Jan

2