physics circuit question

Question

In a parallel circuit, the voltage drop across bulb A is 40.0 V and the voltage drop across bulb C is 15.0 V. Current provided by the battery is 5.0 A and current flowing through bulb B is 3.0 A.

(a) What is the voltage drop across bulb B? (b) How much energy is dissipated by bulb A in one minute?

Answer 1

Because the voltage drops across A and C are different, and the current thru B is less than total current, I can construct a circuit diagram which has A and B in parallel, then C in series on the way back to the battery.

a) Voltage drop across B is therefore 40 Volts.

b) In this scenario, current thru A has to be 5 - 3 = 2 Amps; Power can be written as I*V = (2)(40) = 80 Watts. Since Power is Joules/sec, multiply P by 60 to get Energy dissipated in 1 minute, E = 4,800 J.