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Current Electricity — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsCurrent Electricity1 Mark
MCQ
We are able to obtain fairly large currents in a conductor because
  • A
    The electron drift speed is usually very large
  • ✓
    The number density of free electrons is very high and this can compensate for the low values of the electron drift speed and the very small magnitude of the electron charge
  • C
    The number density of free electrons as well as the electron drift speeds are very large and these compensate for the very small magnitude of the electron charge
  • D
    The very small magnitude of the electron charge has to be divided by the still smaller product of the number density and drift speed to get the electric current
✓

Answer

Correct option: B.
The number density of free electrons is very high and this can compensate for the low values of the electron drift speed and the very small magnitude of the electron charge
(b) This is because of secondary ionisation which is possible in the gas filled in it.

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