Photoelectric Effect Questions and Answers

The potential difference between the plates of a parallel plate capacitor is changing at the rate of 106 V s If the capacitance is 2uF the displacement current in the dielectric of the capacitor will be 1 1 A 2 2 A 3 3 A

When light of frequency 2v and intensity Lilluminates a metal in a photoelectric experiment the stopping potential is 2 V and saturation current is 3 mA Now If the frequency is reduced to one fourth and intensity is doubled the new stopping potential and saturation current are respectively vo is the threshold frequency 1 0 5 V 6 mA 2 0 5 V 3 mA 3 2 V 6 mA 4 0 0

A parallel beam of electromagnetic radiation of wavelength 200 nm is incident on a perfectly reflecting surface The power incident on 1 mm area is 5 x 10 watts Find the pressure exerted by the radiation

The relation between time and displacement for two particles is given by y 0 06 sin 2 0 04t q Y 0 03 sin 2 1 04t The ratio of the intensity of the waves produced by the vibrations of the two particles will be 2 1 1 2 4 1

nucleon E against the nuclear mass M A B C D E F correspond to different nuclei Consider four reactions i A B C E ii C A B iii D E F iv F D E Eb where is the energy released In which reactions is positive A C DE M LL

In a Compton scattering experiment the wavelength of the incident photon is 65 0 pm and the wavelength of the scattered photon is 69 0 pm Calculate the kinetic energy of the recoiling electron O a 2 07 eV O b 1 65 keV O c 0 8 keV O d 4 1 keV e 1 11 kev

Photons with energy 5 eV are incident on 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 1 1 V 2 3 V 3 3 V 4 4 V

When a photon of wavelength 3000 A is incident on a metal surface an electron of energy 0 5 eV is emitte If a photon of wavelength of 2000 A is incident on the metal surface then the energy of emitted electron w be 1 0 5 eV 2 More than 0 5 eV 3 Less than 0 5 eV 4 None of the above

3 A piece of metal has a cutoff wavelength of Acutoff 450 mm Consider illuminating this piece of metal with two different wavelengths of light a 1 500 nm beam and a A2 400 nm beam For each of the two beams find a The maximum kinetic energy of ejected electrons b What is their speed What is their de Broglie wavelength 3

A parallel beam of monochromatic light of wave length 500 nm is incident normally on a perfectly absorb surface The power through any cross section of the beam is 10 W Find a Number of photon absorb by surface per second b The force exerted by light beam on the surface C

If threshold wavelength for a photosensitive plate is 4000 A what will be the value of saturation current if radiation of wavelength 5000 is incident 1 Zero 2 1 mA 3 3 mA 4 Data is insufficient to predict

When you shine 300 nm light on an electrode surface photoelectrons are emitted How many of the metals from the table might the electrode be Explain Potassium 2 30 eVSodium 2 75 eVAluminum 4 28 eVTungsten 4 55 eVCopper 4 65 eVlron 4 70 evGold 5 10 eV JAWNHO 1 2 3 4 5

22 Find the number of electrons emitted per second by a 24 W source of monochromatic light of wavelength 6600 A assuming 3 efficiency for photoelectric effect take h 6 6 10 4 Js 1 48 10 9 2 48 10 7 F 3 3 8 1019 4 24 x 10 7

You shine a monochromatic light with a wavelength of 207 nm on a metal surface The maximum kinetic energy of the electrons emitted from the metal is 6 4x10 19 J What is the work function of the metal O 1 6 10 19 J O 3 2x10 19 J 9 6x10 19 J O 6 4 10 19 J O 1 1x10 18 J

Silver has a work function fo 4 7 eV When ultraviolet light of wavelength 100 nm is incident upon it a potential of 7 7 volt is required to stop the photoelectrons from reaching the collector plate The potential required to stop photo electrons when light of wavelength 200 nm is incident upon silver is A skipped B C 1 5 V 1 85 V 1 95 V 6 7 Correct 0 Wrong 1 MY PERFORMANCE SCORE 1 00 out of 32 F OL

A light detector has an absorbing area of 4 0 x 106 m and absorbs 40 of the incident light which is at wavelength 500 nm The detector faces an isotropic source 10 m from the source The energy E emitted by the source versus time t is given in the figure here E 7 8 nJ t 2 5 s At what rate are photons absorbed by the detector E nJ E 0 N s 1 v