Question

Two charges of 2*10-6c and 1*10-6c are placed at a distance of 10cm. Where shoild be the third charge be placed so no net force is experienced

Answer 1

Hello!!

The third charge would be placed between two charges and 4 cm away from the smaller charge.

The full solution is in the pic.

Hope it helps!

Thanks :)

Answer 2

Given:

First Charge = 2 × 10-6c

Second Charge = 1 × 10-6c

Distance = 10cm

To Find:

Placement of third charge

Solution:

If both the charges are positive, then the third charge needs to be placed on line joining the two charges.

Thus,

F 1  =F  2

2 × q/ r² = 1 × q/(10-r)²

r² = 2(10-r)²

r²= 200 + 2 r² - 40r

 r² - 40r + 200 = 0

r = 40 ± √(1600-800)]/2

= 40 - √(800)/2  since the point should be in between

= 20 - 10√2

= 5.86 cm

Answer : The third charge should be placed at 5.86 cm  from 2×10  −6 C  charge.