Four charges Q 1 , Q 2 , Q 3 and Q 4 of same magnitude are fixed along the x axis at x = - 2 a , - a , + a and + 2 a , respectively. A positive charge q is placed on the positive y axis at a distance

Question

Four charges Q 1 , Q 2 , Q 3 and Q 4 of same magnitude are fixed along the x axis at x = - 2 a , - a , + a and + 2 a , respectively. A positive charge q is placed on the positive y axis at a distance b > 0 . Four options of the signs of these charges are given in List I. The direction of the forces on the charge q is given in List II. Match List I with List II and select the correct answer using the code given below the lists. List I List II A. Q 1 , Q 2 , Q 3 Q 4 all positive P . + x B. Q 1 , Q 2 positive; Q 3 , Q 4 negative Q. - x C. Q 1 , Q 4 positive; Q 2 , Q 3 negative R . + y D. Q 1 , Q 3 positive; Q 2 , Q 4 negative S . - y

TestHub · Accepted Answer

P: By Q 1 and Q 4 , Q 3 and Q 2 F is in +y Q: By Q 1 and Q 4 , Q 2 and Q 3 F is in +ve x. R: By Q 1 and Q 4 , F is in +ve y By Q 2 and Q 3 , F is in -ve y But later has more magnitude, since its closer to (0, b). Therefore net force is in - y S: By Q 1 and Q 4 , F is in +ve x and by Q 2 and Q 3 , F is in -x, but later is more in magnitude, since its closer to (0, b). Therefore net force is in -ve x.

	List I		List II
A.	$Q_{1}, Q_{2}, Q_{3} Q_{4}$ all positive	$P .$	$+ x$
B.	$Q_{1}, Q_{2}$ positive; $Q_{3}, Q_{4}$ negative	Q.	$- x$
C.	$Q_{1}, Q_{4}$ positive; $Q_{2}, Q_{3}$ negative	$R .$	$+ y$
D.	$Q_{1}, Q_{3}$ positive; $Q_{2}, Q_{4}$ negative	$S .$	$- y$

Physics - Electrostatics Question with Solution | TestHub

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