Question

The electric potential decreases uniformly from 180 V to 20 V as one moves on the X-axis from x=-2 cm to x=+2 cm.The electric field at the origin:

• A. must be equal to -40 V/cm
• B. may be equal to 40 V/cm.
• C. may be less than 40 V/cm.
• D. may be less than -40 V/cm.

Answer 1

The correct option is B may be equal to 40 V/cm.

The electric potential decreases uniformly $=180V$ to $20V$

$x=(-2)cm$ to $x=+2cm$

The electric field at the origin $=(-\frac{dV}{dx})$

$=\frac{-(180-20)}{-2-\left(2\right)}$

$=+\frac{160}{4}$

$=40V/cm$

in the positive direction of $x-$axis. Hence, $40V/cm$ be the electric field at the origin.