What wavelength must electromagnetic radiation have if a photon i

Subject

Physics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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61.

What wavelength must electromagnetic radiation have if a photon in the beam has the same momentum as an electron moving with a speed 1.1 x 105 m/s (Planck's constant = 6.6 x 10-34 J-s, rest mass of electron = 9 x 10-31 kg ?

  • 2/3 nm

  • 20/3 nm

  • 4/3 nm

  • 40/3 nm


B.

20/3 nm

Given,

me = mass of electron

     = 9 × 10-31 kg

     = 101 × 105 m/s

Momentum, p = meve

                  p = 9 × 10-31 × 1.1 × 105

                     = 9.9 × 10-26 kg-m/s

From de-Broglie waves

        λ = hp = 6.6 × 10-349.9 × 10-26 m   = 23 × 10-8 m   = 203 × 10-9 m   = 203 nm


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62.

Huygens' wave theory of light cannot explain

  • Diffraction phenomena

  • Interference  phenomena 

  • Photoelectric effect

  • Polarization of light


63.

An electron, a neutron and an alpha particle have same kinetic energy and their de-Broglie wavelength are λe, λn, λα and respectively. Which statement is correct about their de-Broglie wavelengths ?

  • λe > λn > λα

  • λe < λn > λα

  • λe < λn < λα

  • λe > λn < λα


64.

It takes 4.6 eV to remove one of the least tightly bound electrons from a metal surface. When monochromatic photons strike the metal surface, electrons having kinetic
energy from zero to 2.2 eV are ejected. What is the energy of the incident photons ?

  • 2.4 eV

  • 2.2 eV

  • 6.8 eV

  • 4.6 eV


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65.

In an insulator, band gap of the order of

  • 0.1 eV

  • 1 eV

  • 5 eV

  • 100 eV


66.

For a P-N junction diode

  • Forward current in mA and reverse current is in µA

  • Forward current is in µA are reverse current is in mA

  • Both forward and reverse currents are in µA

  • Both forward and reverse currents are in mA


67.

For a Zener diode

  • both p and n regions are heavily doped

  • p region is heavily doped but n region is lightly doped

  • n region is heavily doped but p region is lightly doped

  • both p and n regions are lightly doped


68.

Speech signals is in the range of

  • 3700 Hz to 7000 A wavelength

  • 20 Hz to 20 kHz frequency

  • 300 Hz to 3100 Hz frequency

  • 540 kHz to 1600 kHz frequency


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69.

To transmit a signal of frequency ωm with a carrier frequency ωc, in AM transmission, the bandwidth of the filter and amplifier is

  • ωm

  • m

  • ωc

  • ωc − ωm


70.

Which of the following particle when bombards on 65Cu will turn into 66Cu ?

  • Proton

  • Neutron

  • Electron

  • Alpha particle


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