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1. Electric Charges and Fields
medium
Two particles ${A}$ and ${B}$ having charges $20\, \mu {C}$ and $-5\, \mu {C}$ respectively are held fixed with a separation of $5\, {cm}$. At what position a third charged particle should be placed so that it does not experience a net electric force?
A
At $5\, {cm}$ from $20\, \mu {C}$ on the left side of system
B
At $5\, {cm}$ from $-5 \,\mu {C}$ on the right side
C
At $1.25 \,{cm}$ from $-5\, \mu {C}$ between two charges
D
At midpoint between two charges
(JEE MAIN-2021)
Solution
Null point is possible only right side of $-5 \,\mu {C}$
${E}_{{N}}=+\frac{{k}(-5\, \mu {C})}{{x}^{2}}+\frac{{k}(20 \,\mu {C})}{(5+{x})^{2}}=0$
${x}=5\, {cm}$
Standard 12
Physics
