COMEDK · Physics · 19. Current Electricity
The drift velocity of free electrons in a conducting wire is the order of \(10^{-4} \mathrm{~m} / \mathrm{s}\). Yet, the bulb glows very quickly after the switch is put ON because
- A the random speed of electrons is very high of order of \(10^6 \mathrm{~m} / \mathrm{s}\)
- B the electrons transfer their energy very quickly through collisions
- C electric field is set-up in the wire with a speed of light producing a current through each cross-section, almost instantaneously
- D the random speed of electrons is very low of order of \(10^{-6} \mathrm{~m} / \mathrm{s}\)
Answer & Solution
Correct Answer
(C) electric field is set-up in the wire with a speed of light producing a current through each cross-section, almost instantaneously
Step-by-step Solution
Detailed explanation
When electric field is applied, the random motion of all free electrons converted into uni-directional within very short duration of time of order \(10^{-9} \mathrm{~s}\). Which in turn sets up on electric field instantaneously. Thus, a current through each cross-section is…
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