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QAIPM-2001-Ch-2853: NEET 2002 Physics - Class 12 AIPM-2001-Ch-2853 Solution: Identical charges (-q) are placed at each corner of cube of…
Identical charges (-q) are placed at each corner of cube of side b then electrostatic potential energy of charge (+q) which is placed at centre of cube will be
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Step-by-Step Verified Solution
There are eight corners of a cube and in each corner there is a charge of (�q). At the centre of the corner there is a charge of (+q). Each corner is equidistant from the centres of the cube and the distance (d) is half of the diagonals of the cube.
Diagonal of the cube = b 2 + b 2 + b 2 = 3 b
_ d = 3 b / 2
Now, electric potential energy of the charge (+q) due to a charge (�q) at one corner
U = q 1 q 2 4 � _ 0 r = ( + q ) _ ( _ q ) 4 � _ 0 ( 3 b / 2 ) = _ q 2 2 � _ 0 ( 3 b )
_ Total electric potential energy due to all the eight identical charges
= 8 U = _ 8 q 2 2 � _ 0 3 b = _ 4 q 2 3 � _ 0 b