Q151 / 160 · AP EAMCET 2019 (21 Apr Shift 2) · Physics

Assertion A : The work done by the electrostatic force is zero when a point charge moves in a circular path around another charge.

Reason R : The dot product of force and displacement vectors gives work done.

  • Correct answer
    A
    Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  • B
    Both Assertion and Reason are true but Reason is NOT the correct explanation of Assertion.
  • C
    Assertion is true but Reason is false.
  • D
    Assertion is false but Reason is true.

Solution

When the force is acting at right angle to the direction of
motion of charge, then the work done is zero.
W=Fdcos90°
W=0
The electrostatic force is radially inwards when a point charge moves in a
circular path around another charge.

Therefore, the electrostatic force acts at right angle to the direction of motion of the charge. Hence, work done is zero.

Hence, the correct answer is option: 'A'.

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