Electron Emission

In a discharge tube ionization of enclosed gas is produced due to collisions between:

1. positive ions and neutral atoms/molecules

2. negative electrons and neutral atoms/molecules

3. photons and neutral atoms/molecules

4. neutral gas atoms/molecules

A emits monochromatic light of wavelength When placed away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved away, the number of photoelectrons liberated is reduced by a factor of:
1.
2.
3.
4.

In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by:

1.	increasing the filament current.
2.	decreasing the filament current.
3.	decreasing the potential difference between the anode and filament.
4.	increasing the potential difference between the anode and filament.

Electrons of mass m with de- Broglie wavelength \lambda fall on the target in an X-ray tube. The cut-off wavelength (\lambda _o) of the emitted X-ray is:

1. ${\mathrm{\backslash lambda}}_0=\frac{2{\mathrm{mc\backslash lambda}}^2}{\mathrm{h}}$

2. ${\mathrm{\backslash lambda}}_0=\frac{2\mathrm{h}}{\mathrm{mc}}$

3. ${\mathrm{\backslash lambda}}_0=\frac{2{\mathrm{m}}^2{\mathrm{c}}^2{\mathrm{\backslash lambda}}^2}{{\mathrm{h}}^2}$

4. ${\mathrm{\backslash lambda}}_0=\mathrm{\backslash lambda}$

Which among the following verified the wave nature of electrons experimentally?

1. De-Broglie

2. Hertz

3. Einstein

4. Davisson and Germer

The minimum wavelength of X-rays produced by an electron accelerated through a potential difference of volts is proportional to:
1.
2.
3.
4.