Dual Nature of ...

Photoelectric effect supports quantum nature of light, because
I. there is minimum frequency of light below which no photoelectrons are emitted.
II. electric charge of photoelectrons is quantised.
III. maximum kinetic energy of photoelectrons depends only on the frequency of light and not on its intensity.
IV. even when metal surface is faintly illuminated the photoelectrons leave the surface immediately.

An important spectral emission line has a wavelength of 21 cm. The corresponding photon energy is (h = 6.62 × 10^–34 Js and c = 3 × 10⁸ ms^–1)

X – rays are used to irradiate sodium and copper surfaces in two separate experiments and stopping potential determind. This stopping potential is

Photocell is a device to

An electron and proton are moving with the same speed. Mass of proton =1836 times mass of electron. The ration of their de – Broglie wavelengths will be

The de – Broglie wavelength of a neutron at 927^o C is λ . What will be its wavelength at 27^oC ?

The correctness of velocity of an electron moving with velocity 50ms^-1 is 0.005 %. The accuracy with which its position can be measured will be

An X – ray tube is operated at 20kV. The maximum speed of electrons striking the anticathode will be

When X – rays of wavelength 1Å passes through a gold foil of thikness 2.303 mm , then their intensity reduces to half. The coefficient of absorption for gold (in mm^-1) will be A passes through a gold foil of thikness

An X – rays tube is operated at 50 kV, produce heat at the target at the rate of 796 watt. If 0.5% energy of incident electrons is converted into X –rays,then the number of electrons striking the target per second will be