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Two points charges 20 mu C and 10muC are separated by 1m in air. Find the work done to separate them two metre apart. |
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Answer» Solution :Data SUPPLIED, `r_(1)=1m""r_(2)=2m ""q_(1)=20 xx 10^(-6)C""q_(2)=10 xx 10^(-6)C` For AIR, `epsi_(r)=1` Potential energy `U_(1)=(1)/(4pi epsi_(0)). (q_(1)q_(2))/(r_(1)) and U_(2)-(1)/(4pi epsi_(0)) .(q_(1)q_(2))/(r_(2))` WORK done `W=U_(1)-U_(2) =(1)/(4pi epsi_(0)).q_(1)q_(2) [1/r_(1)-1/r_(2)]=(1)/(4pi epsi_(0)).q_(1)q_(2) ((r_(2)-r_(1))/(r_(1)r_(2)))` `=9 xx 10^(9) xx 20 xx 10^(-6) xx 10 xx 10^(-6) xx ((2-1))/(1 xx 2) ="0.9 joules"` |
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