Photoelectric Effect Questions and Answers

Light of wavelength from a small 0 5mW He Ne laser source used in the school laboratory shines from a spacecraft of mass 1000 kg Estimate the time needed for the spacecraft to reach a velocity of 1 0 km s 1 from rest The momentum p of a photon of wavelength is given by p h 2 where h is Plank s constant A 6 1018 B 3 x 1017 C 6 x 1017 D 2 x 1015

The work function of tungsten is 4 50 eV The wavelength of fastest electron emitted when light whose photon energy is 5 50 eV falls on tungster surface is 1 12 27 2 0 286 3 12400 4 1 227

9xme 2 16 Th present in different wave function for a hydrogen atom is In unit of the difference between energy levels corresponding from 3 to 2 total nodes

The work function of a substance is 4 0 eV The longest wavelength of light that can cuas photoelectric emission from the substance i approximately 1 220 nm 2 310nm

In the figure shown electromagnetic radiations of wavelength 200nm are incident on the metallic plate A The photo electrons are accelerated by a potential difference 10 2 eV These electrons strike another metal plate B from which electromagnetic radiations are emitted The minimum wavelength of the emitted photons is 100nm Find the work function of the metal A in eV use hc 12400 eV 200nm m 100nm 110v

A light beam of wavelength 400 nm is incident on a metal plate of work function 2 2 eV A particular electron absorbs a photon and makes some collisions before coming out of the metal Assuming that 10 of the instantaneous energy is lost to the metal in each collision find the minimum number of collisions the electron can suffer before it becomes unable to come out of metal use hc 12400 eV

D Set The Food 146 Light of wavelength 500 nm is incident on a metal with work function 2 28 eV The de Broglie wavelength of the emitted electron is 2 8 10 9 m 3x16 2 8x10 9 m 2 8 10 12 m 2 8x10 10 in 1 2 11 147 Two metal wires of identical dimensions are connected in series If and a S l 2806 28 146 147

Photons with energy 5 eV are incident on a cathode C in a photoelectric cell The maximum energy of emitted photoelectrons is 2 eV When photons of energy 6 eV are incident on C no photoelectrons will reach the anode A if the stopping potential of A relative to C is NEET Phase 2 2016 1 3 V 2 4 V 3 1 V 4 3 V

32 Figure shows the graph of stopping potential Vo vs frequency v of incident light The slope of the line equals a h energo b he he 2 c e h d h e semaining

If is the thresholdwavelength forphotoelectric emission 2 the wavelength of light falling on the surface of a metalama m is the mass of the electron then the velocity of ejected electron is given by B 2hc m 1 2 71 2 71 2 1 2 1 2 2 D 2 C 2hc2 2 m 2h 1

19 The electron in the hydrogen atom jumps from excited state n 3 to its ground state n 1 and the photons thus emitted irradiate a photosensitive material If the work function of the material is 5 1 eV the stopping potential is estimated to be the energy of the electron in th state En 1 5 1 V 13 6 eV n AIPMT Mains 2010 2 12 1 V 18711

Frequency of a matter wave its equal to KE KE 2 KE h 2h h 1 2 3 4 2

A and B in figure I and II represent two sets shaded area The output represented by the set Y in Figure III is realised by the logic gate 1 OR I A II 2 NOT 3 NOR B III 4 AND Y

E A CD M The above is a plot of binding energy per nucleon E against the nuclear mass M A B C D E correspo to different nuclei Consider four reactions AIEEE 2009 4 144 iv F D E E 1 A B C ii C A B where is the energy released In which reactions 2 ii and iv 1 i and iii 4 i and iv iii D E F and positive 3 ii and iii

6 The approximate wavelength of a photon of energy 2 48 eV is 1 500 3 2000 2 5000 A 4 1000

3 An electron hole pair is formed when light of maximum wavelength 6000 is incident on the The band gap energy of the semiconductor semiconductor a 4 eV is approximately b 0 4 eV d 2 eV

10 From the figure describing photoelectric effect we may infer correctly that Na Al VIL KEA 1 Na and Al both have the same threshold frequency 2 Maximum kinetic energy for both the metals depend linearly on the frequency 3 The stopping potentials are different for Na and Al for the same change in frequency 4 Al is better photosensitive material than Na

85 Surface of certain metal is first illuminated with light of wavelength 350 nm and then by light of wavelength 540 nm It is found that maximum speed of the photo electrons in the two cases differ by a factor of 2 The work function of the metal in eV is close to L double Energy of photon a 1 8 1240 in nm b 1 4 eV c 2 5 d 5 6 JEE 2018

B Two towers on top of two hills are 40 km apart The line joining them passes 50 m above a hill halfway between the towers Longest wavelength of radio waves which can be sent between the towers without appreciable diffraction is 2 25 cm 4 15 cm 1 12 5 cm 3 30 cm

The truth table for the orcuit shown in the figure is A B D

The threshold frequency for a certain metal is 3 3 10 4 Hz If light of frequency 8 2 10 4 Hz incident on the metal then the cut off voltage f the photoelectric emission is approximately 6 V A V d Yu h 5 V

A beam of unpolarised light having flux 103 watt falls normally on a polariser of cross sectional area 3 x 10 m The polariser rotates with an angular frequency of 31 4 rad s The energy of light passing through the polariser per revolution will be A 10 joule B 10 joule C 10 2 joule D 10 joule

PHOTO ELE The energy of photon of visible light with maximum wavelength in eV is 1 1 3 3 2 2 1 6 4 7

of it e 4 5 10 22 44 The work functions for metals A B and C are respectively 1 92 eV 2 0 eV and 5 eV According to Einstein s equation the metals which will emit photoelectrons for a radiation of wavelength 4100 A AIPMT Prelims 2005 is are 2 A only 4 All the three metals doult 1 Conly 3 A and B only

The band gap in germanium is AE 0 68 eV Assuming that the number of hole electron pairs is proportional to e 4k 2kT find the percentage increase in the number of charge carriers in pure germanium as the temperature is increased form 300 K to 320 K

50 For incident frequency n stopping potential is v then for frequency n2 stopping potential is a V b V h n n e h n n e V 11 c V d V2 h n n e h n n e V v

Photoelectric emission is observed for a metallic surface for frequency f and f If maximum kinetic energy of electrons in these two cases are in ratio of 1 n then threshold frequency for metallic surface is given by nf f 1 n 1 2 nf f n 1 3 n f f n 1 nf 4 f nf

Explain the inverse linear dependence potential on the incident in a photoelectric effect of stopping wavelength experiment

A difference of 2 3 eV separates two energy levels in an atom What is the frequency of radiation emitted when the atom make a transition from the upper level to the lower level

he electrons that are used in an electron microscope are accelerated through a potential ifference of 63 0 kV Part A Calculate the speed of the electrons using the Newtonian formula for kinetic energy Express your answer with the appropriate units 0 xa A Xb x 10 FREENE X

ng is directly related to the amount of energy contained within a single photon of light O the frequency of the photon what material the photon hits O the speed of the photon O the brightness of the photon

What causes a gaseous element to emit light its emission spectrum electrons moving into the nucleus O electrons falling from a high energy level to a lower energy level O none of the above O electrons moving from a low energy level into a higher energy level

A periodic wave has a wavelength of 8 4 m and a speed of 14 m s What is the period of the wave

In a photoelectric effect experiment a beam of blue light is incident on a metal plate and does not eject electrons from the plate a State whether each of the following beams of light might be able to eject electrons from this plate Explain your reasoning A beam of red light that is brighter than the blue beam A beam of UV light that is dimmer than the blue beam b The diagram at right shows the electric field of the original beam of blue light On the same axes make a sketch of the red beam of light in part a Explain your reasoning E m

The speed of light is 3 108 m s Find the wavelength for a typical AM radio wave with a frequency of 800 kHz Answer in units of m Answer in units of m part 2 of 2 Find the wavelength for a typical AM radio 6 10 3TT Your response i

The lowest energy photon that can ionize Carbon has an energy of 11 2603 eV What is the wavelength of this photon and in what part of the electromagnetic spectrum is it Note that one form of Planck s constant is h 4 136 10 5 eV sec

D The Energy Level Diagram for Hydrogen is shown below Level n 8 n 6 n 5 n 4 n 3 n 2 lonization Ground State Energy eV 0 00 0 38 0 54 0 85 1 51 40f 3 40 n 1 13 60 Energy Levels for the Hydrogen Atom Kinetic energy a Determine the energy in electron volts of a photon emitted by an electron as it moves from the n 6 to th n 2 energy level in a hydrogen atom b Convert the energy of the photon to joules c Calculate the frequency of the emitted photon Show all work including the equation and substitution with units d Is this the only energy and or frequency that an electron in the n 6 energy level of a hydrogen atom could emit Explain your answer

Electrons are accelerated from rest through an 8000 V potential difference Partsby By what factor would their de Broglie wavelength increase if they were instead accelerated through a 2000 V potential 35 VAE

How many sublevels are there with n 1 in an atom

Part A Determine the energy in eV of a photon with a 650 nm wavelength E Submit Part B VAE Request Answer Determine the wavelength of a 6 0 keV x ray photon eV

The arrows in the diagram is likely to result in continuous emission spectrum not predictable as there are to many energy states involved absorption spectrum line spectrum

4. During a photoelectric effect experiment, light possessing 2.53 eV of energy is incident on the photosensitive material. Electrons are emitted with an energy of 1.71 eV of energy. What is the work function of the material? 2.53 eV 4.24 eV 1.71 eV 0.82 eV

3. The frequency of orange light is 5.01 x 10¹4 Hz. How much-energy does a photon of orange light carry? (h= 6.626 x 10-34 J-s; 1 eV = 1.60 x 10-1⁹ J) 5.43 eV 3.32 eV 2.07 eV 7.56 eV

9. During a photoelectric effect experiment, light possessing 2.53 eV of energy is incident on the photosensitive material. The work function of the material is 0.78 eV What is the kinetic energy of the emitted electrons? 5.30 x 10-19 J 4.05 x 10-19 J 1.25 x 10-19 J 2.80 x 10-19 J

2. What is the de Broglie wavelength of a 2.89 x 10-28 kg particle moving at 3.00 x 108 m/s? (h= 6.626 x 10-34 J-s) 4.45 x 10-15 m 7.65 x 10-15 m 7.99 x 10-15 m 9.12 x 10-15 m

1. What is the de Broglie wavelength of a particle with a momentum of 1.11 x 10-10 kg-m/s? (h= 6.626 x 10^-34 J-s) 5.17 x 10-24 m 3.78 x 10-24 m 5.96 x 10-24 m 6.79 x 10-24 m

2. The frequency of violet light is 7.5 x 10¹4 Hz. How much energy does a photon of violet light carry? (h= 6.626 x 10-34 J-s; 1 eV = 1.60 x 10-¹⁹ J) 3.14 x 10³ ev 2.73 x 10-² ev 0.148 eV 3.11 eV

A cylindrical rod of some laser material 5 x 10-2m long and 10-2m in diameter contains 2 × 1025 ion per m³. If on excitation all the ions are in the upper energy level and de-excite simultaneously emitting photons in the same direction, calculate the maximum energy contained in a pulse of radiation of wavelength 6.6 x 10-7m . If the pulse lasts for 10-7 s, calculate the average power of the laser during the pulse A. 33.55 W B. 43.55 W C. 23.55 W D. 29.55 W

A Laser light of wavelength 600nm is used to weld retina detachment. If a Laser pulse of width 60ms and 0.5kW is used the approximate number of photons in the pulse are: A. 10^20 B. 10^18 C. 10^22 D. 10^19

In Young's double slit experiment the separation d between the slits is 2mm, the wavelength of light used is 5896A and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20°. To increase the angular fringe width to 0.21° (with same > and D) the separation between the slits needs to be changed to.