Verified Solution • 2025–26 Session moderate

QJEEAdv20Pha2e1: JEE Advanced 2020 Physics - Class 12 JEEAdv20Pha2e1 Solution: In an X-ray tube, electrons emitted from a filament (cathode)…

In an X-ray tube, electrons emitted from a filament (cathode) carrying current I hit a target (anode) at a distance d from the cathode. The target is kept at a potential V higher than the cathode resulting in emission of continuous and characteristic X-rays. If the filament current I is decreased to 12, the potential difference V is increased to 2V, and the separation distance d is reduced to d2, then

Multiple Choice Options

  • A the cut-off wavelength will reduce to half, and the wavelengths of the characteristic X-rays will remain the same
  • B the cut-off wavelength as well as the wavelengths of the characteristic X-rays will remain the same
  • C the cut-off wavelength will reduce to half, and the intensities of all the X-rays will decrease
  • D the cut-off wavelength will become two times larger, and the intensity of all the X-rays will decrease

Step-by-Step Verified Solution

λ∝1V

So, when V double, then cut-off wavelength become half. Characteristic does not depend on voltage. When I is halved, then intensity will decrease.

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