The current conduction in a discharge tube is due to:
1. electrons only
2. +ve ions and –ve ions
3. –ve ions and electrons
4. +ve ions and electrons
If a light of amplitude A and wavelength λ is incident on a metallic surface, then the saturation current flow is proportional to (assume cut-off wavelength = ):
1.
2.
3.
4.
A photo-cell is illuminated by a source of light, which is placed at a distance \(d\) from the cell. If the distance becomes \(\frac{d}{2}\), then the number of electrons emitted per second will be:
1. same
2. four times
3. two times
4. one-fourth
When ultraviolet rays strike a metal plate, the photoelectric effect does not occur. It occurs by the incidence of:
1. Infrared rays
2. X-rays
3. Radio wave
4. Lightwave
A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then:
1. | each emitted electron carries one-quarter of the initial energy |
2. | number of electrons emitted is half the initial number |
3. | each emitted electron carries half the initial energy |
4. | number of electrons emitted is a quarter of the initial number |