Advertisements
Advertisements
प्रश्न
Describe the construction of photoelectric cell.
Advertisements
उत्तर १
A photoelectric cell is device which converts light energy into electrical energy. It works on the principle of photoelectric effect.
Construction : A photoelectric cell consist a small evacuated bulb. A thin layer of an alkali metal is deposited on inner surface of the bulb. The bulb is made of quartz, if cell is used with ultraviolet light. If the cell is to be used with visible light only. the bulb is made of ordinary glass. A small portion of the surface of bulb is left uncoated and serves as a window for incoming light. The coated surface of the bulb acts as cathode. The anode is in shape of sphere.
उत्तर २
Construction —
- Photocell consists of evacuated glass tube containing two electrodes emitter (K) and collector (A).
- The emitter is shaped in the form of a semi hollow cylinder. It is always kept at a negative potential.
- The collector is in the form of a matal rod and fixed at the axis of the semi-cylinderical emitter. The collector is always kept as a positive potential.
- The glass tube is fitted on non-metallic base and pins are provided at the base for external connection.
Working —
- The emitter is connected to negative terminal and collector is connected to positive terminal of a battery.
- A radiation of frequency more than threshold frequency of material of emitter is made incident on the emitter. Photo-emissions take place. The photoelectrons are attracted towards the collector which is positive w.r.t the emitter. Thus, current flows in the circuit.
- If the intensity of incident radiation is increased, the photoelectric current increases.
APPEARS IN
संबंधित प्रश्न
The wavelength of light from the spectral emission line of sodium is 589 nm. Find the kinetic energy at which
(a) an electron, and
(b) a neutron, would have the same de Broglie wavelength.
What is the de Broglie wavelength of a dust particle of mass 1.0 × 10−9 kg drifting with a speed of 2.2 m/s?
For what kinetic energy of a neutron will the associated de Broglie wavelength be 1.40 × 10−10 m?
Show that the wavelength of electromagnetic radiation is equal to the de Broglie wavelength of its quantum (photon).
What is the de Broglie wavelength of a nitrogen molecule in air at 300 K? Assume that the molecule is moving with the root-mean square speed of molecules at this temperature. (Atomic mass of nitrogen = 14.0076 u)
Obtain the de Broglie wavelength of a neutron of kinetic energy 150 eV. As you have an electron beam of this energy is suitable for crystal diffraction experiments. Would a neutron beam of the same energy be equally suitable? Explain. (mn= 1.675 × 10−27 kg)
Obtain the de Broglie wavelength associated with thermal neutrons at room temperature (27°C). Hence explain why a fast neutron beam needs to be thermalised with the environment before it can be used for neutron diffraction experiments.
Compute the typical de Broglie wavelength of an electron in a metal at 27°C and compare it with the mean separation between two electrons in a metal which is given to be about 2 × 10−10 m.
A electron of mass me revolves around a nucleus of charge +Ze. Show that it behaves like a tiny magnetic dipole. Hence prove that the magnetic moment associated wit it is expressed as `vecμ =−e/(2 m_e)vecL `, where `vec L` is the orbital angular momentum of the electron. Give the significance of negative sign.
State any one phenomenon in which moving particles exhibit wave nature.
When a light wave travels from air to glass ______.
What are matter waves?
The wavelength of the matter wave is dependent on ______.
The de-Broglie wavelength associated with a material particle when it is accelerated through a potential difference of 150 volt is 1 Å. What will be the de-broglie wavelength associated with the same particle when it is accelerated through a potential difference of 4500 V?
Relativistic corrections become necessary when the expression for the kinetic energy `1/2 mv^2`, becomes comparable with mc2, where m is the mass of the particle. At what de Broglie wavelength will relativistic corrections become important for an electron?
- λ = 10 nm
- λ = 10–1 nm
- λ = 10–4 nm
- λ = 10–6 nm
Assuming an electron is confined to a 1 nm wide region, find the uncertainty in momentum using Heisenberg Uncertainty principle (∆x∆p ≃ h). You can assume the uncertainty in position ∆x as 1 nm. Assuming p ≃ ∆p, find the energy of the electron in electron volts.
A particle A with a mass m A is moving with a velocity v and hits a particle B (mass mB) at rest (one dimensional motion). Find the change in the de Broglie wavelength of the particle A. Treat the collision as elastic.
An electron is accelerated from rest through a potential difference of 100 V. Find:
- the wavelength associated with
- the momentum and
- the velocity required by the electron.
Two particles move at a right angle to each other. Their de-Broglie wavelengths are λ1 and λ2 respectively. The particles suffer a perfectly inelastic collision. The de-Broglie wavelength λ, of the final particle, is given by ______.
The De-Broglie wavelength of electron in the third Bohr orbit of hydrogen is ______ × 10-11 m (given radius of first Bohr orbit is 5.3 × 10-11 m):
An electron of mass me, and a proton of mass mp = 1836 me are moving with the same speed. The ratio of the de Broglie wavelength `lambda_"electron"/lambda_"proton"` will be:
For which of the following particles will it be most difficult to experimentally verify the de-Broglie relationship?
How will the de-Broglie wavelength associated with an electron be affected when the velocity of the electron decreases? Justify your answer.
How will the de-Broglie wavelength associated with an electron be affected when the accelerating potential is increased? Justify your answer.
In \[\lambda=\frac{h}{mv}\], what do \[m\] and \[v\] represent, respectively?
Which wave quantities did de Broglie relate to the particle quantities energy and momentum?
Which phenomenon does the concept of matter waves help explain?
What de Broglie wavelength is obtained for the electron?
