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![[Post New]](/templates/default/images/icon_minipost_new.gif) 3 Jul 2007 23:59:04 IST
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A brass sphere having a positive charge of 1.7 x 10^ -8 c is made to touch another sphere of the same redius having a negative charge of 3 x 10 ^ -9 c. Find the force between them when they are separated bya dist of 20.cm An electron is revolving around a long line charge density 2 x 10 ^ -8 Find the KE of the elestron assuming that it is independent of the radius of electron's orbit.
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4 Jul 2007 00:04:48 IST
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ans 1)
LET CHARGE ON EACH AFTER TOUCHING = Q
={(17 * 10^ -9 ) - (3 * 10 ^-9)} / 2 C
=7 * 10^ -9 C
USING THE VALUE OF Q , CALCULATE F
F= KQ.Q/R^2
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woods are lovely, dark and deep.....
but i have promises to keep....
and miles to go before i sleep....
and miles to go before i sleep.... |
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As for the second question, the electric field due to a wire at a distance R is
( /2  R).
Then force on the electron is (e/2R)
This provides the necessary centripetal force.
mv2/R = (e/2R)
Hence, K = (1/2)mv2 = (e/4)
Substitute the values to get the answer
And plz ask one question at a time
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this reply: 7 points
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