JEE Main 2025 Apr 7 Shift 2, Physics Q1: Gauss's Law
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : The outer body of an air craft is made of metal which protects persons sitting inside from lightning-strikes.
Reason (R) : The electric field inside the cavity enclosed by a conductor is zero.
In the light of the above statements, chose the most appropriate answer from the options given below :
- A
Both (A) and (R) are correct and (R) is the correct explanation of (A)
- B
(A) is correct but (R) is not correct
- C
Both (A) and (R) are correct but (R) is not correct explanation of (A)
- D
(A) is not correct but (R) is correct
This is a direct consequence of the electrostatic shielding property of conductors. Any external electric field, such as that produced by a lightning strike, is completely cancelled inside a cavity enclosed by a conductor, because the charges on the conductor rearrange themselves to make the interior field vanish.
An aircraft's metallic outer shell acts precisely as such a hollow conductor, so people seated inside sit in a field-free region and are protected from lightning. Thus the reason directly explains the assertion.
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