COMPASSLearning
RegisterLogin

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Modern Physics

WhatsApp Email
The threshold wavelength for photoelectric emission from a material is . Photoelectrons will be emitted, when this material is illuminated with monochromatic radiation from a
A. 75 W infra-red lamp
B. 10 W infra-red lamp
C. 75 W ultra-violet lamp
D. 10 W ultra-violet lamp

Choose the correct answer from the options given below :
  1. (A)B and C only
  2. (B)A and D only
  3. (C)C only
  4. (D)C and D only✓ Correct

Answer: (D)

Solution

Photoemission depends only on wavelength, not on power: it occurs when the incident wavelength is shorter than the threshold . Ultraviolet light lies below this threshold while infrared lies above it, so both ultraviolet lamps eject electrons regardless of their wattage, and neither infrared lamp does. Photoelectrons are emitted by the W and the W ultraviolet lamps.

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Single correct option

Practise more: all JEE Main PYQs on Modern Physics →

More JEE Main questions on Modern Physics

  1. 7.9 MeV α-particle scatters from a target material of atomic number 79. From the given data the estimated diameter of nuclei of the target material is (approximately) ______ m.
    [ Nm²/C² and electron charge C]
    JEE Main 2026View solution →
  2. The minimum frequency of photon required to break a particle of mass 15.348 amu into particles is ______ kHz.
    [mass of He nucleus = 4.002 amu, amu kg, J.s and m/s]
    JEE Main 2026View solution →
  3. The smallest wavelength of Lyman series is 91 nm. The difference between the largest wavelengths of Paschen and Balmer series is nearly nm.
    JEE Main 2026View solution →
  4. Light is incident on a metallic plate having work function . If the produced photoelectrons have zero kinetic energy then the angular frequency of the incident light is ______ . ( …
    JEE Main 2026View solution →
  5. The energy of an electron in an orbit of the Bohr's atom is where is the ground state energy. If L is the angular momentum of the electron in this orbit and h is the Planck's constant, then …
    JEE Main 2026View solution →
  6. A particle having electric charge and mass is accelerated by applying an electric potential of 1.21 V . Wavelength of the matter wave associated with the particle is . The va …
    JEE Main 2026View solution →