Consider the circuit of three identical batteries and three identical bulbs conn
ID: 1430940 • Letter: C
Question
Consider the circuit of three identical batteries and three identical bulbs connected exactly as shown here. In this problem, assume that each battery is a perfect physics battery supplying voltage V and the bulbs are perfect ohmic devices with resistance R. A friend of yours says, "That middle battery is hooked up backwards! The bulbs won't light if you hook the circuit up like that." (a) Respectfully and thoroughly explain to your friend that the bulbs will indeed light. (b) Find the voltage drop across each resistor. (c) Find the power dissipated by each bulb and the total power dissipated by the circuit.Explanation / Answer
a)
SInce 2 batteries are hooked in forward direction and 1 in backward.
there is effectively 1 battery in forward direction
This effective 1 battery will drive current in circuit and will make the bulb glow
b)
i = V net / Rnet
= V / 3R
Voltage drop across each resistor will be same
V drop = I*R
= (V/3R) * R
= V/3 volts
c)
Power dissipated by eacg bulb = i^2*R
= (V/3R)^2 * R
= V^2/9R watt
Total power = sum of power dissipated acros each bulb
= 3*V^2/9R
= V^2/3R