Question

Point charges , -4C and 92 - -2C are kept at
point x = 0 and x = 4 respectively, electrical potential
will be zero at points (where x is in cm)
3
8
cm and x = 8 cm
cm and x 6 cm
x = 2 cm and x = 6 cm
x = 1 cm and x = 5 cm
=​

Answer 1

Answer:

8/3 cm and 8 cm

Explanation:

(-4C)<-----r---->•<----4 - r----->(-2C)

In between line of the charges, let it be at 'r' from charge -4C and 4 - r from from -2C. Given,

V(due to -4C) = V(due to - 2C)

=> k (-4)/r = k(-2)/(4 - r)

=> - 4/r = -2/(4 - r)

=> 4(4 - r) = 2r

=> 16 - 4r = 2r

=> 16 = 2r + 4r

=> r = 8/3

(-4C)<--------4unit------>(-2C)<----R - 4----->•

<------------------------ R ------------------------>

Outside the line of charges, let it be at 'R' from -4C and at R - 4 from - 2C.

=> V(due to -4C) = V(due to - 2C)

=> k (-4)/R = k (-2)/(R - 4)

=> 4/R = 2/(R - 4)

=> 4(R - 4) = 2R

=> 4R - 16 = 2R

=> 4R - 2R = 16

=> R = 8

Option A