Electric charges of 1,μ C,, - 1,μ C and 2,μ C are placed in air at corners A , B and C respective

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1. Electric Charges and Fields

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Electric charges of $1\,\mu C,\, - 1\,\mu C$ and $2\,\mu C$ are placed in air at the corners $A$, $B$ and $C$ respectively of an equilateral triangle $ABC$ having length of each side $10 \,cm$. The resultant force on the charge at $C$ is......$N$

A

$0.9$

B

$1.8$

C

$2.7$

D

$3.6$

Solution

(b) $F_A$ = force on $C$ due to charge placed at $A$
$ = 9 \times {10^9} \times \frac{{{{10}^{ – 6}} \times 2 \times {{10}^{ – 6}}}}{{{{(10 \times {{10}^{ – 2}})}^2}}} = 1.8\,N$
$F_B$ = force on $C$ due to charge placed at $B$
$ = 9 \times {10^9} \times \frac{{{{10}^{ – 6}} \times 2 \times {{10}^{ – 6}}}}{{{{(0.1)}^2}}} = 1.8\,N$
Net force on $C$
${F_{net}} = \sqrt {{{({F_A})}^2} + {{({F_B})}^2} + 2{F_A}{F_B}\cos {{120}^o}} = 1.8\,N$

Standard 12

Physics

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