Home
Class 12
PHYSICS
A free pith ball of mass 6g carries a po...

A free pith ball of mass `6g` carries a positive charge of `(1//3) xx 10^(-7) C`. What is the nature and magnitude of charge that should be given to a second pith ball fixed `5 cm` vertically below the former pith ball so that the upper pith ball is stationary.

Text Solution

Verified by Experts

The upper pith ball will become stationary only when its weight acting downwards is balanced by the upward force of repulsion between the two pith balls. Let `+ q_(2)` be the change given to lower pith ball.
Now, `q_(1) = (1)/(3) xx 10^(-7) C`.
`r = 5 cm = 5xx10^(-2) m`,
`m = 6 g = 6xx10^(-3) kg`
When upper pith ball is stationary, `F = mg`
`:. (1)/(4pi in_(0)) (q_(1) q_(2))/(r^(2)) = mg`
`(9xx10^(9)xx(1)/(3)xx10^(-7) q_(2))/((5xx10^(-2))^(2)) = 6xx10^(-3)xx9.8`
`(3xx10^(2))/(25xx10^(-4))q_(2) = 58.8xx10^(-3)`
`q_(2) = (58.8xx25)/(3) xx 10^(-9) = 4.90xx10^(-7) C`
Promotional Banner

Similar Questions

Explore conceptually related problems

A free pith ball p of 10g carries of 5xx10^(-8) C . What must be the nature and maganitude fo charge that should be given to another pith ball Q fixed 7 cm below the former ball, so that upper ball is statinary ?

A pith-ball A of mass 9xx10^(-5) kg carries a charge of 5 mu C. What must be the magnitude and sign of the charge on a pith-ball B held 2 cm directly above the pith-ball A, such that the pith-ball A remains stationary ?

A very tiny ball of mass 20 g carries a positive charge 0.04 muC . It is held stationary in air due to electric force by a charge fixed below it at a distance of 10 cm. What should be the magnitude and nature of charge ?

Electric force experienced by a charge of 1 muC is 5 xx 10^(-3) N. What should be the magnitude of electric field intensity at the position of the charge?

A pith ball carrying a charge of 3 xx 10^(-10) C is suspended by an insulated thread of length 50 cm .When a uniform electric filed is applied in a horizontal direction , the ball is found to deflect by 2 cm from the vertical. If the mass of the ball is 0.5 gm , the intensity of the electric field is :

A positively charged glass rod is brought near an uncharged pith ball penduium. What happens to the pith ball ?

Two pith balls , of mass 10 mg, are suspended from the same point,each by a silk fibre 50 cm long . When equal and similar changes are given to them, they are repelled to a distance of 10 cm from each other. Calculate the chagre on either ball .

A small ball of paper has mass 9xx10^(-5) kg and carries a charge of 5muC . When it is held over another charged ball of paper at a distance of 2cm above it, the two balls stay in equilibrium. What is the charge on the second hall ?

A ball of mass 10^(-2) kg and having charge + 3 xx 10^(-6)C is tied at one end of a 1m along thread. The other end of the thread is fixed and a charge - 3 xx 10^(-6) C is placed at this end. The ball can move in the circulr orbit of radius 1m in the vertical plane. Initially, the ball is at the bottom. Find the monimum initial horizontal velocity of the ball, so that it will be able to complete the full circle.