If the minimum energy of photons needed to produce photoelectrons is 3 eV, bombardinbg the photoelectric material by a number of photons of 2.5 eV also one can get
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(a) Photoelectrons of […]
A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of 3 x 10⁶ ms⁻¹. The velocity of the particle is
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(a) 3 x 10⁻³¹ […]
Calcium plate has a maximum possible radiation wavelength 400 nm to eject electrons. Its work function is
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(a) 23 eV (b) 3.1 eV (c) 4.5 eV (d) None of these
Correct Answer: […]
A light of wavelength 5000Å falls on a sensitive plate with photoelectric work function 1.90 eV. Kinetic energy of the emitted photoelectrons will be (given, h=6.62×10⁻³⁴ Js)
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(a) 0.1 eV (b) 2 […]
Bragg’s law for X-rays is
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(a) d sin θ = 2nλ (b) 2d sin θ = nλ (c) n sin θ = 2λd (d) None of these
Correct Answer:
2d sin θ […]
Electrons with energy 80 keV are incident on the tungsten target of an X-ray tube. The K-shell electrons of tungsten have -72.5 keV energy. The X-rays emitted by the tube contains only
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A charged oil drop is suspended in a uniform field at 3×10⁴ V/m so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge=9.9×10⁻¹⁵ kg and […]
An α-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb m⁻². The de-Broglie wavelength associated with the particle will be
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(a) […]
Electrons in a certain energy level n=n₁, can emit 3 spectral lines. When they are in another energy level, n=n₂. They can emit 6 spectral lines. The orbital speed of the electrons in the two […]
In a laser tube, all the photons
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(a) have same energy (b) have same wavelength (c) move in same direction (d) move with same speed
Correct Answer:
move with same speed
Explanation: […]
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