Advertisements
Advertisements
प्रश्न
Define the term ‘stopping potential’ in relation to photo-electric effect.
उत्तर
If we increase the negative potential of the collector, the photoelectric current decreases rapidly. At a certain critical value of the negative potential of the collector, the photoelectric current becomes zero. This potential is called stopping potential or cut-off potential and it depends on the frequency of the incident radiation, but independent of its intensity.
APPEARS IN
संबंधित प्रश्न
Calculate the wavelength of radiation emitted when electron in a hydrogen atom jumps from n = `oo` to n = 1.
State clearly how photoelectric equation is obtained using the photon pictu.re of electromagnetic radiation.
Write the three salient features observed in photoelectric effect which can be explained using this equation.
Cathode rays constitute a stream of _______________ .
Which of the following is true for a cathode ray?
(a) It travels in a straight line.
(b) It emits an X-ray when it strikes a metal.
(c) It is an electromagnetic wave.
(d) It is not deflected by a magnetic field.
The saturation current in a triode valve can be changed by changing _____________ .
A discharge tube contains helium at low pressure. A large potential difference is applied across the tube. Consider a helium atom that has just been ionised due to the detachment of an atomic electron. Find the ratio of the distance travelled by the free electron to that by the positive ion in a short time dt after ionisation.
Two discharge tubes have identical material structures and the same gas is filled in them. The length of one tube is 10 cm and that of the other tube is 20 cm. Sparking starts in both the tubes when the potential difference between the cathode and the anode is 100 V. If the pressure in the shorter tube is 1.0 mm of mercury, what is the pressure in the longer tube?
Which of the following proves particle nature of light?
Assertion A: The photoelectric effect does not takes place, if the energy of the incident radiation is less than the work function of a metal.
Reason R: Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal.
