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Dual Nature of Radiation and Matter · Question 69

AIPMT 2005MCQEasy📈 Topic in 75% papers+4−1
1

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 is/are

  1. A only
  2. A and B only
  3. all the three metals
  4. none

Answer

(2) A and B only

Solution

Energy of the incident photon:

E = hc = 12400 eV A4100 A

3.02 eV

Photoemission occurs only when E 0 (work function),

A: 0 = 1.92 eV < 3.02 eV ⇒ emits

B: 0 = 2.0 eV < 3.02 eV ⇒ emits

C: 0 = 5 eV > 3.02 eV ⇒ no emission

Only metals A and B emit photoelectrons.

Answer: (2)

AIPMT 2005

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2

A photosensitive metallic surface has work function, h 0. If photons of energy 2h 0 fall on this surface, the electrons come out with a maximum velocity of 4 106 m/s. When the photon energy is increased to 5h 0, then maximum velocity of photoelectrons will be

  1. 2 107 m/s
  2. 2 106 m/s
  3. 8 106 m/s
  4. 8 105 m/s
AIPMT 2005
3

According to Einstein's photoelectric equation, the graph between the kinetic energy of photoelectrons ejected and the frequency of incident radiation is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2004
4

A photoelectric cell is illuminated by a point source of light 1 m away. When the source is shifted to 2 m then

  1. each emitted electron carries one quarter of the initial energy
  2. number of electrons emitted is half the initial number
  3. each emitted electron carries half the initial energy
  4. number of electrons emitted is a quarter of the initial number
AIPMT 2003
5

J.J. Thomson's cathode-ray tube experiment demonstrated that

  1. cathode rays are streams of negatively charged ions
  2. all the mass of an atom is essentially in the nucleus
  3. the e/m of electrons is much greater than the e/m of protons
  4. the e/m ratio of the cathode-ray particles changes when a different gas is placed in the discharge tube
AIPMT 2003
6

The value of Planck's constant is

  1. 6.63 10-34 J/sec.
  2. 6.63 10-34 kg-m2/sec2
  3. 6.63 10-34 kg-m2
  4. 6.63 10-34 J-sec.
AIPMT 2002
7

If particles are moving with same velocity, then which has maximum de Broglie wavelength?

  1. proton
  2. -particle
  3. neutron
  4. -particle
AIPMT 2002
8

When ultraviolet rays are incident on a metal plate, photoelectric effect does not occur. It occurs by incidence of

  1. infrared rays
  2. X-rays
  3. radio waves
  4. microwaves
AIPMT 2002
9

Which of the following is not the property of cathode rays?

  1. It produces heating effect
  2. It does not deflect in electric field
  3. It casts shadow
  4. It produces fluorescence.
AIPMT 2002
10

Which one among the following shows particle nature of light?

  1. photoelectric effect
  2. interference
  3. refraction
  4. polarization
AIPMT 2001
11

A photo-cell is illuminated by a source of light, which is placed at a distance d from the cell. If the distance becomes d/2, then number of electrons emitted per second, will be

  1. remain same
  2. four times
  3. two times
  4. one-fourth
AIPMT 2001

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