Consider two horizontal parallel plates. The upper plate has a voltage differenc
ID: 1266115 • Letter: C
Question
Consider two horizontal parallel plates. The upper plate has a voltage difference of 30 V with the lower plate, and they are separated by 3 cm. You move the two plates carefully to a separation of 4 cm. What is the strength of the electric field between the plates?
A. 3000 volts/meter
B. 1000 volts/meter
C. 750 volts/meter
D. 7.5 volts/meter
E. 75 volts/meter
If a charge of -3 x 10-6 C were allowed to fall through a potential difference of +500 V, the change in potential energy for the charge would be
A. -1.5
Explanation / Answer
electric field remain unchanged in capacitor is battery is not connected
so the electric field is E
E = V / d
E = 30 / 3 * 10^-2
E = 1000 V/m
potential energy = q * V
potential energy = -3 * 10^-6 * 500
potential energy = -1.5 * 10^-3 J
negative amount of work is to be done to bring a negative charge from an infinitely great distance away into the presence of a positive charge