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CBSE Class 12-science Answered

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Asked by r01raunak | 23 May, 2023, 10:24: AM
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The question is guessed from the scribbling shown in the image as follows
 
" It is required to find the location of null electric field between the charges 30 μC and 40 μC if the distance between two charges is 20 m" 
 
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Let us assume that at point P which is at a distance x m from 30 μC charge we have null electric field .
 
Let E1 and E2 be the electric field due to 30 μC and 40 μC charge respectively. 
 
begin mathsize 14px style E subscript 1 space equals space K space asterisk times space fraction numerator 30 space cross times space 10 to the power of negative 6 end exponent over denominator x squared end fraction end style
where K = 1 / (4 πεo ) is Coulomb's constant . 

begin mathsize 14px style E subscript 2 space equals space K space asterisk times space fraction numerator 40 space cross times space 10 to the power of negative 6 end exponent over denominator left parenthesis 20 minus x right parenthesis squared end fraction end style
 
If we get null electric field at P , then E1 = E2
 
begin mathsize 14px style 30 over x squared space equals space 40 over left parenthesis 20 minus x right parenthesis squared end style
 
begin mathsize 14px style 40 space x squared space equals space 3 space left parenthesis 20 space minus space x space right parenthesis squared space end style
 
begin mathsize 14px style space square root of 4 over 3 end root space x space equals space left parenthesis space 20 space minus x space right parenthesis end style
 
1.155 x = (20 -x )
 
2.155 x = 20 
 
x = 20 / 2.155 = 9.28 m
 
Hence at a distance 9.28 m from 30 μC charge , we get zero electric field

Answered by Thiyagarajan K | 23 May, 2023, 11:32: AM

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