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Consider the charges q.q and -qplaced at the vertices of an equilateral triangles as .Showin figure. What is the force on each charges?(##JYT_AJP_AIO_PHY_XII_C01_SLV_011_Q01.png" width="80%"> |
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Answer» Solution :The FORCES acting on charges Q at A due to charges q at B and -q at C are `F_(12) `along BA and `F_(12) `along AC respectively as shown in figure. Bythe parallelogram law. The total force ` F_1 ` on the charges q at A is given by `F_1 = F hatr_(1) "where " HATR _1 ` is a unit vector along BC. The force of atraction or repulsion for each pair of charges has the same magnitude ` F-(q^(2))/( 4pi in _0l^(2))` The total force ` F_2`on charges q at B is thus `F_2 =F HAT r _2.` where hat `r_2` is a unit vector along AC Similarlythe total force on charge -at C is ` F_3= sqrt 3 hatn " where "hat n`is the unit vector along the direction bisecting the `angle BCA ` The sum of the forces on the three chargesis zero, i.e. ` F_1+F_2+F_3=0 ` (for the system) The result follows straight from the fact that Coulomb.s law is consistant with Newton.s third law. |
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