Question

Equipotential surfaces are shown in figure. Then the electric field strength will be ______.

Options

• 100 vm^-1 along X-axis 

• 100 Vm^-1 along Y-axis 

• 200 vm^-1 at an angle 120° with X-axis 

• 50 vm^-1 at an angle 120° with X-axis

Answer 1

200 vm^-1 at an angle 120° with X-axis 

Explanation:

Using dV = `-vec"E"."d"vec"r"`

⇒ ΔV = -E Δr cos θ

⇒ E = `(-Delta"V")/(Delta"r"costheta)`

⇒ E = `(-(20-10))/(10xx10^-2cos120°)`

= `(-10)/(10xx10^-2(-sin30°))`

= 200 V/m

Direction of E be perpendicular to the equipotential surface i.e. at 120° with X-axis.