Photoelectric Effect Questions and Answers

3 37 If light of wavelength of maximum intensity emitted from a surface at temperature T is used to cause photoelectric emission from a metallic surface the maximum kinetic energy of the emitted electron is 6 eV which is 3 times the work function of the metallic surface If light of wavelength of maximum intensity emitted from a surface at temperature T T 2T is used the maximum kinetic energy of the photoelectrons emitted is a 2 eV c 14 eV b 4 eV d 18 eV

48 In the following arrangement y 1 0 mm d 0 24 mm and D 1 2 m The work function of the material of the emitter is 2 2 eV The stopping potential V needed to stop the photocurrent will be Bright Dark 1 Bright Dark Bright a 0 9 V y D Its S

2 15 Monochromatic light of frequency fis incident on emitter having threshold frequency fo The kinetic energy of ejected electron will be a hf b h f f c hf d h f f

2 NO 22 The adjoining figure shows the variation of photo current with anode potential for a photosensitive surface for three different radiations Let I I and I be the intensities and f f and f be the frequencies for the curves a b and c respectively Then a urdu 0 a ff and 1 1 c f f and I a 2 2 Anode potential b f f and I 1 d 200 4

1 Photoelectric emission is observed from a metallic surface for frequencies v and v of the incident light v v If the maximum values of kinetic energy of the photoelectrons emitted in the two cases are in the ratio 1 n then the threshold frequency of the metallic surface is a C 1 1 n 1 nv v n 1 b d nv v n 1 1 1 n

Is True but the Reason is False D If both Assertion and Reason are False 1 Assertion The strength of photoelectric current depends upon the intensity of incident radiation Reason A photon of energy E possesses a mass equal to E c and momentum equal to E c 2 Assertion Though light

6 Assertion Light described at a place by the equation E E sin cot sin 7cot falls on a metal surface having work function The maximum kinetic energy of the 7ho photoelectron is KE max 2 r sepe 0 Reason Maximum kinetic energy of photoelectron depends on the maximum frequency present in the incident light according to Einstein s photoelectric effect equation

EP 3 Consider a 100 W bulb emitting light in all directions Suppose that a metallic Na surface is kept at a distance of 1m from the bulb Estimate the time needed by an electro in a Na atom to receive 1 eV energy assuming all energy absorbed by top surface and all energy given to Na atom is taken by 1 electron

An isolated conducting sphere is bombarded by photons of 180nm wavelength As electrons are ejected the sphere will become charged If the Binding Energy of the sphere material is 4 0eV what voltage will the sphere be able to reach a 4 0V b 2 9V c 2 0V d 2 9V 4 OV el

The potential energy of a particle of mass m is given by U x 0 x 1 and x 1 respectively If the total mechanical energy of particle is 2Eo find 01 02 03 Eo 0 x 1 to X 1 and 2 are the de broglie wave lengths of the particle when Joh 0 O 1 2

greater ener A TV station is operated at 100 MW with a signal frequency of 10 MHz Calculate the number of photons radiated per second by its antenna

1 5mW of 4000 A light is directed at a photoelectric cell If 0 10 percent of the incident photons produce photoelectrons find current in the cell Given h 66 x 10 4 Js c x 3 108 ms 1 and e 1 6 10 C 1 0 50 4

A moving hydrogen atom absorbs a photon and comes to rest What is the maximum possib wavelength of photon hc 12420 eV Find wavelength in Your Answer 9 132 Correct Answer Rate

Q7 90 In the given figure the energy levels of hydrogen atom have been shown along with some transitions marked as AB C D E 0 54 eV 0 85 eV 1 51 eV 3 4 CV 13 6 eV B C infrared ultraviolet visible D ultraviolet infrared infrared ultraviolet infrared visible In which part of the electromagnetic spectrum does A B C transitions lie visible ultraviolet infrared n 5 n 4 n 1

A certain metal has a Fermi energy of 3 50 eV Find the number of electrons per unit volume with energy between 4 50 eV and 4 60 eV for T 290 K T 2480 K Use values from this ta a T 290 K b electrons per m T 2480 K electrons per m

Suppose radiation from a black body is allowed to fall on a photosensitive material after passing it through a filter which selects the wavelength having maximum intensity to pass The work function of the material is 1 24 V Find the minimum temperature in 10 K of the black body which will cause the emission of photo electrons Given Weins constant b 3 x 10 m K hc 12400 eV A

3 A beam of electromagnetic radiation of intensity 6 4 x 10 5 W cm is comprised of wavelength 310 nm It falls normally on a metal work function 2eV of surface area of 1 cm If one in 103 photons ejects an electron total number of electrons ejected in 1s is 10 he 1240 eVnm leV 1 6x10 19 J then x is

What is the work function of the metal if the light of wavelength 4000 generates photoelectrons of velocity 6 x 105 ms 1 form it Mass of electron 9 x 10 1 kg Velocity of light 3 108 ms 1 Planck s constant 6 626 10 4 Js Charge of electron 1 6 10 JeV 1

The electric field associated with a monochromatic beam becomes zero 1 2 10 5 times per second Find the maximum kinetic energy of the photoelectron when this light falls on a metal surface whose work function is 2 0 eV

a De exci www photon emitted emitted photon energy hf E E tion Excited states are usually very unstable Within about 10 6s the electron will fall back to a lower energy level With each fall in energy level level E down to level E a photon of electromagnetic radiation is emitted

1 Light of wavelength 0 6 m from a sodium lamp falls on a photocell and causes the emission of photoelectrons for which the stopping potential is 0 5 V With light of wavelength 0 4 um from a sodium lamp stopping potential is 1 5 V With this data the value of h e is n x 10 15 Vs Find value of n

6 Light of wavelength 330 nm falling on a piece of metal ejects electrons with sufficient energy which requires voltage Vo to prevent them from reaching a collector In the same setup light of wavelength 220 nm ejects electrons which require twice the voltage Vo to stop them in reaching a collector The numerical value of 15 voltage Vo is V Find value of x X

value 9 The kinetic energies of the photoelectrons ejected from a metal surface by light of wavelength 2000 range from zero to 3 2 x 10 19 Joule Then find the stopping potential in V

The de broglie wavelength of electrons striking the cathode to produce x rays is equal minimum wavelength of x ray produced What is the voltage across x ray tube in volt 1 100

Two separate monochromatic light beams A and B of the same intensity are falling normally on a unit area of a metallic surface Their wavelength are and respectively Assuming that all the incident light is used in ejecting the photoelectrons the ratio of the number of photoelectrons from the beam A to that from B is 1 3 A 2 B 4 1 MP0118 No of photoelectrom Intensity of light T

When light of intensity 1 W m and wavelength 5 10 7m is incident on a surface it is completely absorbed by the surface If 100 photos emit one electron and area of the surface is 1 cm then the photoelectric current will be

The surface temperature of the sun is To and it is at an average distance d from a planet The radius of the sun is R If 0 is the angle subtended by the sun at the planet the steady state temperature of the planet is proportional to Radius of planet r d

4 5 mW of 400 nm light is directed at a photoelectric cell If 0 10 of the incident photons produce photoelectrons the current in the cell is 1 1 45 A 2 0 48 A 4 0 32 mA 3 0 42 mA

U 4 A beam of monochromatic light of wavelength 6600A is incident normally on a perfectly absorbing surface The power of the beam is 30 W The number of photons absorbed per second by the surface is 1 1018 2 1019 3 1020 4 1021

In the following YDSE arrangement y 1 mm d 0 24 mm and D 1 2 m If the light emitted from the source S is incident on the photo sensitive surface of work function 2 2 eV then stopping potential for electron ejected from the center of screen will be 1 0 9 V Bright Dark Bright Dark Bright D 2 0 5 V 01015

Monochromatic light strikes a diffraction grating at normal incidence before illuminating a screen 2 50 m away If the first order maxima are separated by 1 43 m on the screen what is the distance between the two second order maxima 2 29 m 2 39 m 4 21 m

periment of photo electric effect Kmax for photo electrons is Ko If frequency of light is doubled then Ka of Kmax if frequency of light is trippled 4 Ko 5 Ko 6 Ko

An electron of mass m with an initial velocity 4 V voi vo 0 enters an electric field Ei E constant 0 at t 0 If is its de Broglie wavelength initially then its de Broglie wavelength at time t is NEET 2018 1 1 3 20 e Eo mvo t 2 201 4 t e Eo t mvo 9 Photons wi cathode C energy of e photons o photoelec stopping B 1 3 2 4 3 1 4 3

19 A radioactive material of half life T was produced in a nuclear reactor at different instants the quantity produced second time was twice of that produced first time If now their present activities are A and A2 respectively then their age difference equals T a In 2 In T c In In 2 2A A A 2A b T In A1 A d T In A 2A

The energy equivalent of 0 5 g of a substance 1 0 5 1013 J Jon s 2 4 5 1016 J 3 4 5 x 1013 J 4 1 5x 1013 J a s 015X0

3 When a light beam of frequency v is incident on a metal surface photoelectrons are emitted If these electrons describe a circle of radius r in a magnetic field of strength B then the work function of the metal is EAMCET 2015

A beam of light has two wavelength 4972 and 6216 A with a total intensity of 3 6 x 10 3 Wm 2 equally distributed among the two wavelengths The beam falls normally on an area of 1 cm of a clean metallic surface of work function 2 3 eV Assume that there is no loss of light by reflection and that each capable photon ejects one electron The number of photo electrons liberated in 2s is approximately A B skipped C C 6 x 10 1 9 1011 11 1011 15x 1011 QU 6 Coff MY PE SC 4

89 Light of wavelength strikes a photoelectric surface and electrons are ejected with an energy E If E is to be increased to exactly twice its original value the wavelength changes to where a is less than 2 b is greater than 2 c is greater than 2 but less than d X is exactly equal to 2

A photon has the same wavelength as the de Broglie wavelength of electron Given that c speed of light and v speed of electron Which of the following relation is correct Here E Kinetic energy of energy of photon Pe e momentum of electron Eph electron and Pph momentum of photon Ee V Ee 2c a Eph c Pe n V 2c 12 b Eph d Pe Pph 2c Pe C 2v

Using radiation of wavelength 3500 it is observed that the maximum kinetic energy of the emitted photoelectrons is 1 6 eV for potassium Calculate the work function of the metal h 6 626 X 10 34 Js 1 eV 1 6 x 10 19 J 1 3 eV 2 2 5 eV 3 3 5 eV 4 2 eV

A photosensitive metallic surface has work function 6 If photon of energy 30 fall on this surface the electron comes out with a maximum velocity of 6x 106 ms When the photon energy is increased 1 T to ap then max velaity of photo eultro one 6X106 mis 84 X ta t HO

D The work function of a metal is 1 eV Light of wavelength 3000 is incident on this metal surface The velocity of emitted photoelectrons will be a 10 ms 1 c 1 104 ms 1 b 1x 10 ms 1 d 1 x 106 ms 1

eV If radiations of 2000 A fall on the metal then the kinetic energy of the fastest photo electron is 1 1 6 x 10 19 J 2 16 x 1010J 3 3 2 x 10 19 J 4 6 4 x 10 10J

59 From the figure describing photoelectric effect we may infer correctly that Stopping potential Na Al 0 0 Frequency a Na and Al both have the same threshold frequency b Maximum kinetic energy for both the metals depend linearly on the frequency c The stopping potentials are different for Na and Al for the same change in frequency d Al is better photosensitive material than Na

Select the correct statements Pleas e find the question in the image below 11 Select the correct statements 1 In the energy levels of a certain atom when the system emitted The wavelength 2 of the photon produced moves from 2E to E level a photon of wavelength is durign the transition from level 4E 3 to level E is 2 2E 4E 3 E 2 2 7 2 In the photo electric effect the solpe of straight line graph between stopping potential Vo and frequency of incident light v gives ratio of h planck s constant and charge on electron e V Vo 3 The graph for the stopping potential Vo vs v frequency for two photoelectric surfacess A and B is shown as V A B The graph shows that work function of B is greater than that of A 4 In the emission of electrons from a metal sarface when exposed to light radiation of appropriate wavelength 2 the kinetic energy of photo electrons emitted does not depend on intensity but depends on frequency of the incident radiation Respected SME please give the solutio n for the above question in the most de tailed manner so that it is easy for me t o understand

a A gas of hydrogen atoms in their ground state is bombarded by electrons with kinetic energy 12 5 eV What emitted wavelengths would you expect to see b What if the electrons were replaced by photons of same energy OCU

15 The work function for tungsten and sodium are 4 5 eV and 2 3 eV respectively If the threshold wavelength A for sodium is 5600 then the value of 2 for tungsten is a 5893 c 2862 b 10683 d 528 52

41 In a photoelectric experiment the relation between applied potential difference between cathode and anode V and the photoelectric current I was found to be shown in graph 3 2 O V in volt below If Planck s constant h 6 6 10 34 Js the x frequency of incident radiation would be nearly in s a 0 436 10 8 b 0 436 10 7 d 0 775 10 6 c 0 775x 10 5 Maximum KE of a photoelectron is F when th

a c n n 5 When light of wavelength 300 nm falls on a photoelectric emitter photoelectrons are liberated For another emitter light of wavelength 600 nm is sufficient for liberating photoelectrons The ratio of the work function of the two emitters is a 1 2 c 4 10 b 2 1 d 1 4 in the

A solar sail consists of a very light thin plane surface which can absorb all the photons incident on it Consider such a sail placed at a very large distance from the sun normal to the direction of incident radiation What is the mass per unit area of the sail such that it will neither be blown away nor be pulled in by the sun Given Mean distance of the earth from the sun semi major axis 1 5 10 km Intensity of solar radiation outside the earth s atmosphere 1 4 kW m Speed of light 3 108 m s Take 1 earth year 107 s Express your answer in ma m2 and round off to the nearest integer