Question
Define the terms threshold frequency and stopping potential in relation to the phenomenon of photoelectric effect. How is the photoelectric current affected on increasing the (1) frequency (2) intensity of the incident radiations and why?

Answer

  1. Threshold frequency:
The minimum frequency of the incident radiation for a given metal below which emission of photo electrons does not take place.
  1. Stopping potential:
The minimum negative potential of the anode collector for which photoelectric current becomes zero.
  1. (1) (Practically) No effect/remain same.
As increase in frequency does not significantly change the number of photons in the beam.

(2) Increases:

The number of incident photons increases.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

  1. Six lead-acid type of secondary cells each of emf 2.0 V and internal resistance $0.015\Omega$ are joined in series to provide a supply to a resistance of $8.5\ \Omega.$ What are the current drawn from the supply and its terminal voltage?
  2. A secondary cell after long use has an emf of 1.9 V and a large internal resistance of $380\ \Omega$ What maximum current can be drawn from the cell? Could the cell drive the starting motor of a car?
The final volume of a system is equal to the initial volume in a certain process. Is the work done by the system necessarily zero? Is it necessarily non-zero.
Explain, with the help of a circuit diagram, the working of a photo-diode. Write briefly how it is used to detect the optical signals.
Which among the curves shown in figure cannot possibly represent electrostatic field lines?
(a) A closed loop is held stationary in the magnetic field between the north and south poles of two permanent magnets held fixed. Can we hope to generate current in the loop by using very strong magnets?
(b) A closed loop moves normal to the constant electric field between the plates of a large capacitor. Is a current induced in the loop (i) when it is wholly inside the region between the capacitor plates (ii) when it is partially outside the plates of the capacitor? The electric field is normal to the plane of the loop.
(c) A rectangular loop and a circular loop are moving out of a uniform magnetic field region (Fig. 6.8) to a field-free region with a constant velocity $v$. In which loop do you expect the induced emf to be constant during the passage out of the field region? The field is normal to the loops.
Image
(d) Predict the polarity of the capacitor in the situation described by Fig. 6.9.

Image
Plot a graph showing the variation of binding energy per nucleon as a function of mass number. Which property of nuclear force explains the approximate constancy of binding energy in the range 30 < A < 170? How does one explain the release of energy in both the processes of nuclear fission and fusion from the graph?
A thin but long, hollow, cylindrical tube of radius r carries a current i along its length. Find the magnitude of the magnetic field at a distance $\frac{\text{r}}{2}$ from the surface (a) inside the tube (b) outside the tube.
A vector $\overrightarrow{\text{A}}$ makes an angle of 20° and $\overrightarrow{\text{B}}$ makes an angle of 110° with the X-axis. The magnitudes of these vectors are 3 m and 4 m respectively. Find the resultant.
Show that it is not possible for a photon to be completely absorbed by a free electron.
A monochromatic light source of intensity 6mW emits $8 \times 10^{16} $ photons per second. This light ejects photoelectrons from a metal surface. The stopping potential for this setup is 2.0V. Calculate the work function of the metal.