Question

The electric potential decreases uniformly from $120$ V to $80$ V as one moves on the X-axis from x $=$ -1 cm to x $=$ $+1$ cm. The electric field at the origin :

• A. must be equal to $20$ V/cm
• B. may be equal to $20$ V/cm
• C. may be greater than $20$ V/m
• D. may be less than $20$ V/cm

Answer 1

The correct option is A must be equal to $20$ V/cm

As the electric potential decreases uniformly so the electric field is uniform along the x axis.

$E=-\frac{dV}{dx}=\frac{120-80}{1-(-1)}=20$V/m. It must be equal to 20 V/m at the origin.