If the potential difference applied to an X-ray tube is doubled while keeping the separation between the filaments and the target as same, what will happen to the cutoff wavelength?

Question

Question

This question was previously asked in

NDA (Held On: 23 Apr 2017) General Ability Test Previous Year paper

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Answer 1

CONCEPT:

The instrument which is used for the production of X-ray beams using fast cathode rays is known as X-ray tube.

For an X-ray tube relation between stopping potential and minimum energy of X-ray beam is can be given as

Where E_minimum = The energy of X-ray beam, V₀= Stopping potential, h = Plank’s constant, c = Speed of light and λ_cut-off = Cutoff Wavelength

CALCULATION:

Given that

Stopping potential is increases twice hence V₂ = 2V₀ where V₁ = V₀,

∴ Cut off potential when stopping potential is V_o

Cut off potential when stopping potential is doubled, then

Hence

From this we can say that the cutoff wavelength becomes half when stopping potential is increased to twice its initial value.