Related InterviewSolutions

• Light of intensity l is incident perpendicularly on a perfectly reflecting plate of area A kept in a gravity free space. If the photons strike the plate symmetrically and initially the springs were at natural lengths, what is the maximum compression A. `(IA)/(Kc)`B. `(2Ia)/(3Kc)`C. `(3Ia)/(Kc)`D. `(4Ia)/(3Kc)`
• A. How many photons of a tradiation of wavelength `lamda=5xx10^(-7)` m must fall per second on a blackened plate in order to produce a force of `6.62xx10^(-5)`N? B. At what rate will the temperature of plate rise if its mass is 19.86kg and specific heat is equal to `2500J(kgK^(-1))`?A. `3xx10^(19)`B. `5xx10^(22)`C. `2xx10^(22)`D. `1.67xx10^(18)`
• A. How many photons of a tradiation of wavelength `lamda=5xx10^(-7)` m must fall per second on a blackened plate in order to produce a force of `6.62xx10^(-5)`N? B. At what rate will the temperature of plate rise if its mass is 19.86kg and specific heat is equal to `2500J(kgK^(-1))`?
• The frequency and intensity of a light source are both doubled. Consider the following statements A. The saturation photocurrent remains almost the same B. The maximum kinetic energy of the photoelectrons is doubleA. Both A and B are trueB. A is true but B is falseC. A is false but B is trueD. Both A and B are false
• Photoelectric threshold of silver is `lamda=3800A`. Ultraviolet light of `lamda=2600A` is incident of a silver surface.(Mass of the electron `9.11xx10^(-31)kg`)` 1. Calculate the value of work function is eV.A. 1.77B. 3.27C. 5.69D. 2.32
• In question 23, if the intensity of light is made 4 I, the saturation current will becomeA. `0.4 mu A`B. `0.4xx2 mu A`C. `1.6 mu A`D. `0.4xx16 mu A`
• In the previous question, if the intensity of light is made `4I_0`, then the stopping potential will becomeA. `1.36xx1V`B. `1.36xx2V`C. `1.36xx3V`D. `1.36xx4V`
• (a) Photoelectric threshold of metallic silver is `lambda =3800 Å`. Ultravilolet light of `lambda =260` nm is incident on silver surface. Calculate : (i) the value of work function in joule and eV `K_(max)` of the emitted photoelectrons (iii) `v_(max)` of the photoelectrons (b) Ultraviolet light of wavelength 280 nm is used in an experiment on photoelectric effict with lithium `(phi =2.5 eV)` cathode. Find (i) the maximum kinetic energy of the photoelectrons (ii) the stopping potential (c) Find the maximum magnitude of the linear momentum of a photelectron emitted when light of wavelength 400 nm falls on a metal `(phi =2.5 eV)`. (d) A monochromitc light source of intensity 5 mW emits `8xx10^(5)` photons per second. This light ejects photoelectrons from a metal surface. The stopping potential for this set up is `2.0 V` . Calculate the work function of the metal. (e) The maximum kinetic energy of photoelectrons emitted from a certain metallic surface is 30 eV when imonochromatic radiation of wavelength `lambda` falls on it. When the same surface is illuminated with light of wavelength `2 lambda` the maximum kinetic energy of photo electrons is observed to be 10 eV. Calculate the wavelength `lambda` and determine the maximum wavelength of incident radiation for which photoelectrons can be emitted by this surface.
• A totally reflecting, small plane mirror placed horizontally faces a parallel beam of light as shown in the Fig. The mass of the mirror is 20 g. Assume that there is no absorption in in the lens and that `30%` of the light emitted by the source goes through the lens. Find the power (in`xx10^(8)`W) of the source needed to support the weight of the mirror. Take `g=10ms^(-2)`
• Some questions (Assertion-Reason Type) are given below. Each question contains Statement I (Assertion) and statement II(reason). Each question has 4 choices (a),(b),(c ) and (d) out of which only one is correct. So select the correct choise. a. Statement I is True, Statement II is True,Statement II is a correct explanation for Statement I b. Statement I is True, Statement II is True, Statement II is NOT a correct ecplanation for Statement I c. Statement I is True, Statement II is False . d. Statement I is false, Statement II is True. 1. A proton and an electron both have energy 50 eV. Statement I: Both have different wavelength. Statement II: Wavelength depends on energy and not on mass.