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A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?
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- The angular width of the central maximum of the diffraction pattern will increase.
- The angular width of the central maximum will decrease.
- The angular width of the central maximum will be unaffected.
- Diffraction pattern is not observed on the screen in case of electrons.
Correct Option: B
Angular width,
| θ = | = | |||
| D | dD |
 | ∴ Y = |  | ||||
| d |
| So, θ = | , v ↑ λ ↓ θ ↓ | d |
[For central maxima n = 1]
Hence, with increase in speed of electrons angular width of central maximum decreases.
