Photoelectric Effect Questions and Answers

Graph is plotted between photo current 1 and applied voltage V Then maximum kinetic energy of emitted electron will be 1 2 eV 4 3 2 1 0 1 V 2 4 eV 2 3 4 3 0 eV 4 1 eV BOAI BO PHYSICS BOON Z E MODERN PHYS Z WODE02 BOA BO PHYSICS AT A GLANCE CROPEN E screen will be 1 0 9 L 3 0 4

22 A small plate of metal work function 1 17 eV is placed at a distance of 2 m from a monochromatic light source of wavelength 4 8 x 1077 m and power 1 0 W The light falls normally on the plate If a constant uniform magnetic field of strength 10 4T is applied parallel to the metal surface find the radius of the largest circular path followed by the emitted photoelectrons in m

Draw the circuit diagram of a half wave rectifier Explain its working What is the frequency of ripple in its output Why do we need filters in a power supply

1 A photoelectron is moving with a maximum velocity of 106 m s Given e 1 6 x 10 9 c and m 9 1 x 10 1 kg the stopping potential is 1 2 5 V 3 2 0 V 2 2 8 V 4 1 4 V

When radiation of frequency 3 x 1015 Hz incident on a metallic surface having work function 4 eV The minimum velocity of photoelectron is 1 1 72 x 106 ms 1 ayon is 3 10 5 KE Wo4ev 2 3 44 106 ms 1 3 6 88 106 ms 1 4 Zero Vmin 2 6 6x10 KE

If Amin is minimum wavelength produced in X ray tube and is the wavelength of k line As the operating tub woltage is increased A increases min 3 increases NUGA 2 A decreases 4 decreases photo electric cell and

2R A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in uniform magnetic field What should be the energy of an a particle to describe a circle of same radius in the same field 1 2 MeV 2 1 MeV 0 5 MeV 4 4 MeV AIPMT 2012 Mains magnetic field requires J of work to turn it through 60 The torque

37 The diagram shows the energy levels for an electron in a certain atom Which transition shown represents the emission of a photon with the most energy a IV I II b III III IV c II n 4 n 3 n 2 n 1 d I

The threshold frequency for a metallic surface corresponds to an energy of 6 2 eV and the stopping potential for a radiation incident on this surface is 5 V The incident radiation lies in a ultra violet region c visible region b infra red region d X ray region

The spectral emissive power E for a body at temperature T is plotted against the wavelength and area under the curve is found to be A At a different temperature T the area is found to be 9A Then 2 2 1 3 IdE d 2 2 T T 1 2 1 3 ATTE P

An X ray photon of wavelength and frequency collides with an intially stationary electron but free to move 1 and bounces off If y and are respectively the wavelength and frequency of the scattered photon then O X X v v O X dir r V O X X r OX A r

The ionization potential of H atom is 13 6 V Photons of energy 12 75 eV are made to incident on sample of H atoms at ground state How many spectral lines are expected in emitted radiation 1 2 3 4 2 6 4 1

1 An electron having kinetic energy ko collides with a hydrogen atom in the ground state This collision will be elastic if 1 3 4 eV k 10 2 eV 2 k 10 2 eV 3 k 10 2 eV k 10 2 eV

If de broglie wavelength of a particle is 2 then calculate de broglie wavelength of He on accelerating across same potentia difference A 2 2 C 22 B 2x D

Which of the following radiations has the least wavelength 1 y rays 2 B rays 3 rays 4 X rays If the termpreature of the sun were to increase from T to 2T and its radius from R to 2R then the ratio of the radiant AIEEE 2003

Two particles A and B of de Broglie wavelength AA and Ag are in motion in one dimension They combine to form a particle C This process conserves momentum The incorrect relation of de Broglie wavelength of C in relation to that of A and B is 0 010 0 AAXAS AA AB XA XAB 8 1 A AXAB AXAR

If in an excited state of hydrogen atom n 5 then value of n I m s will l be 1 5 4 4 12 2 f hydrogen atom 1 2 7 7 5 4 8 7 5 2 2 is 1 7 x 10 27 kg and inter atomic distance is 4 x 10 10 m Then mor 3 6 6 5 ARKINGA 1

mc h The photoelectric threshold wavelength of silver is 3250 x 10 10 m The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength 2536 x 10 10 m is Given h 4 14 x 10 5 eV s and c 3 x 10 ms 1 0 6 10 ms NEET 2017 MI 2 61 10 ms 3 0 3 10 ms 4 6 10 ms Proglic wavelength of a neutron in thermal equilibrium with heavy water at a temperature T kelvin and mas INEET 2017

D H 2V 2 3V 3 5V An electron in the hydrogen atom jumps from excited state n to the ground state The wavelength so emitted illumi nates a photosensitive material having work function 2 75 eV If the stopping potential of the photoelectron is 10 V the value of n is AIPMT 2011 4 3 2 4 3 5 4 2 for a photon to be emitted by hydrogen atom according t 2011

When a metallic surface is illuminated with radiation of wavelength the stopping potential is V If the same surface is illuminated with radiation of wavelength 22 the stopping potential is V 4 The threshold wavelength for the metallic surface is NEET 2016 1 A 2 32 3 42 4 52 F The ratio of de Broglie wavelengths associated with

neutron 2 deutron 3 alpha 4 tritium The threshold frequency for a photosensitive metal is 7 x 1013 Hz If light of frequency 10 4 Hz is incident on metal then maximum kinetic energy of emitted electron is AIIMS 20 1 4 x 10 20 J 2 8 x 10 20 J 3 2 x 10 20 J ric affect is seen only when electron are bound 4 10 20 J AIIMS 20

Modern Phys A photon of wavelength less than threshold wavelength A is incident on a metal surface of work function W The de Broglie wavelength of the ejected electron of mass m is RPMT 2014 h he 1 h 2m E W 2 2m w W he W 0 X h he 2m W 2 hc 4 h 2m Wo

4 kinetic energy of emitted photoelectrons decreases If wavelenth of photo is 6000 then its energy will be 3 2 66 eV 2 1 66 eV 1 0 66 eV 4 3 5 eV The energy of an electron in the excited state of H tom is 1 5 eV then according to Bohr model

10 58 eV In photo emissive cell with exciting wavelength the fastest electron has speed v If the exciting wavelength changed to 32 4 the speed of the fastest emitted electron will be 1 v 3 4 2 2 v 4 3 2 3 less than u 4 3 2 4 greater than u 4 3 2 The rphotoelectric work function for a metal surface is 4 125 eV The cut off wavelength for this surface is

Which of the following statement is true about de Broglie wavelength of moving ball in cricket 1 de Broglie s theory does not apply on such a big body 2 h 2mE 3 E h 2mE

1 proton 2 a particle 3 Neutron 4 B particle When ultraviolet rays incident on metal plate then photoelectric effect does not occur it occur by incidence of 4 Light wave 1 Infrared rays X2 X rays 3 Radio wave which of the following is not the property of cathode rays

3 will remain constant 4 will either increase or decrease A point source causes photoelectric effect from a small metal plate Which of the following curves may represent the saturation photocurrent as a function of the distance between the source and the metal 1 current distance current distance current distance current distance of 106 What is the diameter of the tenth orbit

The stopping potential necessary to reduce the photoelectric current to zero 1 is directly proportional to wavelength of incident light 2 uniformly increases with the wavelength of incident light 3 directly proportional to frequency 4 uniformly increases with the frequency

photoelectrons emitted from a metal surface The 1 Are all at rest 2 Have the same kinetic energy 3 Have the same momentum 4 Have speeds varying from zero up to a certain maximum value

An a particle is accelerated from rest through a potential of V volts Its final kinetic energy is 4 90 mJ 1 2 eV 2 1 eV 3 4 eV 4 1 eV

A light of amplitude A and wavelength is incident on a metallic surface then saturation current flows is proportional to assume cut off wavelength A A A if2 20 B A if o C A if 20 D A if o

4 Depends both on the intensity and frequency of the incident When stopping potential is applied in an experiment on photoelectric effect no photocurrent is observed This that 1 the emission of photoelectrons is stopped 2 the photoelectrons are emitted but are reabsorbed by the emitter metal 3 the photoelectrons are accumulated near the collector plate 4 the photoelectrons are dispersed from the sides of the apparatus T11

4 the photoelectrons are disper If the frequency of light in a photoelectric experiment is doubled then stopping potential will be doubled 2 be halved 3 become more than double 4 become less than double

An image of the sun is formed by a lens of focal length 30 cm on the metal surface of a photo electric cell and in produces a current I The lens forming the image is then replaced by another lens of the same diameter but of foca length 15 cm The photoelectric current in this case will be In both cases the plate is kept at focal plane and norm to the axis lens 1 1 2 2 21 3 I 4 41

3 twice the original value Mark the correct statement In photo electric effect electrons are emitted from metal surface when light falls on it 2 the kinetic energy of photo electrons is more for light of longer wavelength in comparison to that due to shorter wavelength 3 both of the above 4 none of the above longth of light for photoelectric effect from sodium surface is 6800 A then

In Y D S E distance between slits and screen is 1 5 m when light of wavelength 500 nm is used then 2nd bright fringe is obtained on a screen at a distance of 10 mm from central bright fringe what will be the shift in position of 2nd bright fringe if light of wavelength 550 nm is used Question Type Single Correct Type 1 1 mm 2 11 mm 3 2 mm 4 10 mm

3 A metallic surface when illuminated with light of wavelength A emits electrons with energies upto a maximum value E and when illuminated with light of wavelength A2 where A it emits electrons with energies upto a maximum value E2 Prove that plank s constant h and the work function of the metal are given by h E E A A C A and B A B A 1 1

4 Light of wavelength 800 nm is shone on a metal surface connected to a battery The work function of the metal is 1 25 eV Find the extinction voltage or retarding voltage at which the photoelectron current stops Find the highest speed of the emitted photoelectrons at this incident frequency Ans Vr 0 3 volt 3 2 105m s

A light of wavelength 414 nm falls on a metal surface having work function 1 eV Kinetic energy of fastest moving electron will be hC 1242 eV nm Only one correct answer A 3 eV B C 2 eV 1 eV

tric experiment is performed at two different light intensities I and 1 1 Choose the correct graph showing the variation of stopping potential versus frequency of light 1 12 1 2 12 4 3 v fi fi L fo I 4 None of these

An intense light source radiate uniformly in all directions At a distance of 5 0 m from the source the radiation pressure on the perfectly absorbing surface is 9 0 x 10 6 Pa What is total average power output of the source Question Type Single Correct Type 1 649 KW

Two identical photocathode receive light of frequencies f and f2 If the velocities of the photoelectrons of mass m coming out are respectively v and v then Question Type Single Correct Type 1 v v2 2 V V 3 2h f f 2h f f2 12 f f 2h 12h 1 2 11 2

A particle of mass m confined between 0 x l has a probability 64 of occupying the ground state and a probability 36 of occupying the first excited state The average energy of the particle is Select one a 1 04 n ml b 0 36 2mL c 0 64 n mL2 d 1 04 n ml

b A sample of Ge is doped to the extent of 10 4 donor atoms cm and 7x10 3 acceptor atoms cm At temperature of the sample the resistivity of pure intrinsic Ge is 60 cm If the applied voltage is 2 V cm find the total conduction current density Here mobility of electron is 3800 cm V sec Mobility of holes is 1800 cm V sec 4

Bon excited to a level by a radiation of wavelength 2 When the ion gets de excited to the ground state in all possible ways including intermediate emissions a total of six spectral lines are observed What is the value of Given h 6 63 10 34 Js c 3 108 ms JEE MAIN 2019 81

29 30 4 Streams of neutrons Cathode rays are streams of fast moving 29 farcir fari aftur negative charged particles Their speed range c 3 108 m s consider c 3 x 108 m s 1 0 1 c to 0 2 c 2 c 3 Greater than c 4 Around 10 c to 10 c Photoemission of electrons 30 1 0 1 c to 0 2 c 2 c 3 c 4 10 c to 10 c ll fuck ufc 94

A zinc ball of radius R 1 cm charged to a potential 0 5 V The ball is illuminated by a monochromatic ultraviolet UV light with a wavelength 290 nm The photoelectric threshold for zinc is 332 nm The potential of ball after a prolonged exposure to the UV is A 0 5 V B 0 V C 0 54 V D 0 79 V

The work function of a metallic surface is 5 01 eV The photoelectrons are emitted when light of wavelength 2000 falls on it The potential difference applied to stop the fastest photoelectron is h 4 14 x 10 15 eV O 1 2 V O 2 24 V O 3 6 V O 4 8 V

The de Broglie wavelength of neutron in thermal equilibrium at temperature T is nearly h 6 63 x 10 34 SI units kg 1 38 x 10 23 SI units m 1 67 x 10 27 kg 1 3 30 8 T 0 308 A 3 08 2 4 0 0308

A p n junction photodiode is fabricated from a semiconductor with band gap of 2 2 eV It can detect a light of wavelength 6000 nm 5000 700 nm 6000