Photoelectric Effect and WaveParticle Duality Physics - Photoelectric Effect and WaveParticle Duality

The frequency and intensity of a light source are both doubled. Consider the following statements.

1. The saturation photocurrent remains almost the same.
2. The maximum kinetic energy of the photoelectrons is doubled.

1. Both A and Bare true.
2. A is true but B is false.
3. A is false but B is true.
4. Both A and B are false.

Two photons having:

1. Equal wavelengths have equal linear momenta.
2. Equal energies have equal linear momenta.
3. Equal frequencies have equal linear momenta.
4. Equal linear momenta have equal wavelengths.

A point source of light is used in a photoelectric effect. If the source is removed farther from the emitting metal, the stopping potential:

1. Will increase.
2. Will decrease.
3. Will remain constant.
4. Will either increase or decrease.

The equation E = pc is valid:

1. For an electron as well as for a photon.
2. For an electron but not for a photon.
3. For a photon but not for an electron.
4. Neither for an electron nor for a photon.

A sphere of radius 1.00cm is placed in the path of a parallel beam of light of large aperture. The intensity of the light is 0.5W/cm^-2. If the sphere completely absorbs the radiation falling on it, find the force exerted by the light beam on the sphere.

Can a photon be deflected by an electric field? By a magnetic field?

Consider the situation described in the previous problem. Show that the force on the sphere due to the light falling on it is the same even if the sphere is not perfectly absorbing.

In an experiment on photoelectric effect, a photon is incident on an electron from one direction and the photoelectron is emitted almost in the opposite direction. Does this violate conservation of momentu?

An atom absorbs a photon of wavelength 500nm and emits another photon of wavelength 700nm. Find the net energy absorbed by the atom in the process.

Calculate the momentum of a photon of light of wavelength 500nm.

A photographic film is coated with a silver bromide layer. When light fells on this film, silver bromide molecules dissociate end the film records the light there. A minimum of 0.6eV is needed to dissociate a silver bromide molecule. Find the maximum wavelength of light that can be recorded by the film.

A parallel beam of monochromatic light of wavelength 663nm is incident on a totally reflecting plane mirror. The angle of incidence is 60° and the number of photons striking the mirror per second is 1.0 × 10¹⁹. Calculate the force exerted by the light beam on the mirror.

If an electron has a wavelength, does it also have a colour?

It is found that photosynthesis starts in certain plants when exposed to the sunlight but it does not start if the plant is exposed only to infrared light. Explain.

A totally reflecting, small plane mirror placed horizontally faces a parallel beam of light, as shown in the figure. The mass of the mirror is 20g. Assume that there is no absorption in the lens and that 30% of the light emitted by the source goes through the lens. Find the power of the source needed to support the weight of the mirror. Take g = 10m/s².

Can we find the mass of a photon by the definition p = mv?

A hot body is placed in a closed room maintained at a lower temperature. Is the number of photons in the room increasing?

A silver ball of radius 4.8cm is suspended by a thread in a vacuum chamber. Ultraviolet light of wavelength 200 run is incident on the ball for some time during which a total light energy of 1.0 × 10^-7J falls on the surface. Assuming that on the average one photon out of every ten thousand is able to eject a photoelectron, find the electric potential et the surface of the bell assuming zero potential at infinity. What is the potential at the centre of the bell?

The work function of a photoelectric material is 4.0eV.

1. What is the threshold wavelength?
2. Find the wavelength of light for which the stopping potential is 2.5V.

In an experiment on photoelectric effect, the emitter and the collector plates are placed et a separation of 10cm and are connected through en ammeter without any cell A magnetic field B exists parallel to the plates. The work function of the emitter is 2.39eV and the light incident on it has wavelengths between 400nm and 600nm. Find the minimum value of B for which the current registered by the ammeter is zero. Neglect any effect of space charge.

A light beam of wavelength 400 run is incident on a metal plate of work function 2.2eV.

1. A particular electron absorbs a photon and makes two collisions before coming out of the metal. Assuming that 10% of the extra energy is lost to the metal in each collision, find the kinetic energy of this electron as it comes out of the metal.
2. Under the same assumptions, find the maximum number of collisions the electron can suffer before it becomes unable to come out of the metal.

When the sun is directly overhead, the surface of the earth receives 1.4 × 10³ W m^-2 of sunlight. Assume that the light is monochromatic with average wavelength 500nm and that no light is absorbed in between the sun and the earth's surface. The distance between the sun and the earth is 1.5 × 10¹¹m.

1. Calculate the number of photons falling per second on each square metre of earth's surface directly below the sun.
2. How many photons are there in each cubic metre near the earth's surface at any instant?
3. How many photons does the sun emit per second?