What does this symbol represent in a circuit?
a. cell
b. buzzer
c. capacitor

There is no commonly used circuit symbol that looks just like that.  But there are two symbols that are close.  I guess your drawing could be a slightly incorrect form of either one of them.

I'll show you both of them.

Look at the drawing I attached to this answer.

answer: point c: b. 1/2 potential, 1/2 kinetic, point a: 3/4 of its potential energy, point d or b: 3/4 potential, 1/4 kinetic

explanation: i cant explain. it's difficult to explain.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27