Question

Two parallel plates are 4cm apart and are at potentials $300V$ and $-100V$ respectively. The potential at a distance $3cm$ from $-100V$ plate will be

• A. $300V$
• B. $100V$
• C. $250V$
• D. $150V$

Answer 1

Answer: (B)

$100V$

$V_1$ = 300 V

$V_2$ = -100 V

d = 4 cm = 0.04 m

Electric field between the plates , E = $\frac{-(V_2-V_1)}{d}$

= $\frac{-(-100-300)}{0.04}$

= $\frac{400}{0.04}$

= ${10}^4$ V/m

3 cm from -11 V plate means 1 cm from 300 V plate.

Hence, Potential at a distance 3 cm from -100 V plate = Ed

= ${10}^4\ast 0.01$

= 100 V

Option B