Question

Two 3.0 g spheres on 1.0 m-long threads repel each other after being equally charged, as shown in the figure.

What is the charge q?

http://farm5.static.flickr.com/4050/4296660084_be175edea1_o.jpg

Answer 1

VISUALIZE

The above figure shows the free-body diagram of each point charge of charge q.

Let T be the tension in the each string. And F is the Coulombic force of repulsion acting between both charges.

Components of force acting on the charge q are

………………….. (1)

…………………. (2)

KNOWN

Massof each point charge

Length of each string

Acceleration due to gravity is

FIND

We have to determine the value of the chargeof each point charge.

SOLVE

From the above figure,

Therefore the separation between the two charges is

Let q is the charge of each point charge.

Then according to the Coulombic force of repulsion between the two point charges is

………………. (3)

Dividing the equations (1) and (2) we get