Dual Nature of Radiation and Matter

For a metal of work function 6.6 eV, which of the following wavelengths of incident radiation does not give rise to the photoelectric effect? (Take Planck's constant as 6.6 10-34 J s)

1. 200 nm
2. 100 nm
3. 50 nm
4. 150 nm

A photon and an electron, each of 20 eV energy, move in free space. The ratio of linear momentum of electron pe to that of photon pPh, pepPh is: [Take speed of light = 3 108 m s-1, charge of electron = -1.6 10-19 C and mass of electron = 9 10-31 kg]

1. 275
2. 2450
3. 1250
4. 225

A beam of light falls on a metal surface such that photo-electrons are generated. If power of the light source starts to decrease linearly with time t, then variation of the photocurrent I and magnitude of the stopping potential |V| with time is best represented by:

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A ray of light with wavelength is incident on three different photoelectric cells namely 1, 2 and 3. The threshold wavelength of these photoelectric cells are 1, 2, and 3, respectively and the magnitude of stopping potentials of these cells are V1, V2 and V3, respectively. The relation between and threshold wavelengths are 1 < , 2 > and 3 . The correct option is:

1. V1 < V2, V3 = 0
2. V1 = 0, V2 < V3
3. V1 = 0, V2 > V3
4. V1 > V2, V3 = 0

Which of the following options represent the variation of photoelectric current with property of light shown on the x-axis? [figure]

1. A and D
2. B and D
3. A only
4. A and C

A photon and an electron (mass m) have the same energy E. The ratio ( photon/ electron) of their de Broglie wavelengths is: (c is the speed of light)

1. c 2mE
2. 1c E/2m
3. E/2m
4. c 2mE

The graph which shows the variation of ( 1 2 ) and its kinetic energy, E is (where is de Broglie wavelength of a free particle):

1. [figure]
2. [figure]
3. [figure]
4. [figure]

If c is the velocity of light in free space, the correct statements about photon among the following are: Choose the correct answer from the options given below:

1. A and B only
2. A, B, C and D only
3. A, C and D only
4. A, B, D and E only

An electron and an alpha particle are accelerated by the same potential difference. Let e and denote the de-Broglie wavelengths of the electron and the alpha particle, respectively, then:

1. e >
2. e = 4
3. e =
4. e <

If is the work function of photosensitive material in eV and light of wavelength of numerical value = hce metre, is incident on it with energy above its threshold value at an instant then the maximum kinetic energy of the photo-electron ejected by it at that instant (Take h-Planck's constant, c-velocity of light in free space) is (in SI units):

1. e + 2
2. 2e -
3. e - e
4. e +

The work functions of Caesium (Cs), potassium (K) and sodium (Na) are 2.14 eV, 2.30 eV and 2.75 eV respectively. If incident electromagnetic radiation has an incident energy of 2.20 eV, which of these photosensitive surfaces may emit photoelectrons?

1. Both Na and K
2. K only
3. Na only
4. Cs only

The minimum wavelength of X-rays produced by an electron accelerated through a potential difference of V volts is proportional to :

1. 1V
2. 1 V
3. V2
4. V

When two monochromatic lights of frequency, and 2 are incident on a photoelectric metal, their stopping potential becomes Vs2 and Vs respectively. The threshold frequency for this metal is

1. 2
2. 3
3. 23
4. 32

The graph which shows the variation of the de Broglie wavelength ( ) of a particle and its associated momentum (p) is

1. [figure]
2. [figure]
3. [figure]
4. [figure]

The light rays having photons of energy 4.2 eV are falling on a metal surface having a work function of 2.2 eV. The stopping potential of the surface is

1. 6.4 V
2. 2 eV
3. 2 V
4. 1.1 V

The threshold frequency of a photoelectric metal is 0. If light of frequency 4 0 is incident on this metal, then the maximum kinetic energy of emitted electrons will be :

1. 4h 0
2. h 0
3. 2h 0
4. 3h 0

The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600 nm, when it delivers the power of 3.3 10-3 watt will be : (h = 6.6 10-34 J s)

1. 1015
2. 1018
3. 1017
4. 1016

An electromagnetic wave of wavelength ' ' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength d, then :

1. = ( 2hmc ) d2
2. = ( 2mhc ) d2
3. d = ( 2mch ) 2
4. = ( 2mch ) d2

Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. What will be the photoelectric current if the frequency is halved and intensity is doubled?

1. four times
2. one-fourth
3. zero
4. doubled

The energy required to break one bond in DNA is 10-20 J. This value in eV is nearly :

1. 0.6
2. 0.06
3. 0.006
4. 6

An electron is accelerated from rest through a potential difference of V volt. If the de-Broglie wavelength of the electron is 1.227 10-2 nm, the potential difference is :

1. 102 V
2. 103 V
3. 104 V
4. 10 V

An electron is accelerated through a potential difference of 10,000 V. Its de Broglie wavelength is (nearly) : (me = 9 10-31 kg)

1. 12.2 10-12 m
2. 12.2 10-13 m
3. 12.2 10-14 m
4. 12.2 nm

An electron of mass m with an initial velocity v = v0 i (v0 > 0) enters an electric field E = -E0 i (E0 = constant > 0) at t = 0. If 0 is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is

1. 0 (1 + eE0mv0t )
2. 0 (1 + eE0mv0t )
3. 0t
4. 0

When the light of frequency 2 0 (where 0 is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is v1. When the frequency of the incident radiation is increased to 5 0, the maximum velocity of electrons emitted from the same plate is v2. The ratio of v1 to v2 is

1. 1 : 2
2. 1 : 4
3. 4 : 1
4. 2 : 1

The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature T (kelvin) and mass m, is

1. h 3mkT
2. 2h 3mkT
3. 2h mkT
4. h mkT

An electron of mass m and a photon have same energy E. The ratio of de-Broglie wavelengths associated with them is

1. c(2mE) 12
2. 1c ( 2mE ) 12
3. 1c ( E2m ) 12
4. ( E2m ) 12

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 2 , the stopping potential is V4. The threshold wavelength for the metallic surface is

1. 52
2. 3
3. 4
4. 5

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

1. +3 V
2. +4 V
3. -1 V
4. -3 V

A photoelectric surface is illuminated successively by monochromatic light of wavelength and /2. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is (h = Planck's constant, c = speed of light)

1. 2hc
2. hc3
3. hc2
4. hc

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

1. 2.8 10-9 m
2. 2.8 10-12 m
3. < 2.8 10-10 m
4. < 2.8 10-9 m