# Homework Help: Voltage of bulb in the circuit

1. May 26, 2015

### Max T

1. The problem statement, all variables and given/known data
What is the voltage of the bulb D? Given the total voltage supplied by the cells is 4 watts and each bulb is identical and has a resistance of 3 ohms

2. Relevant equations
V=IR

3. The attempt at a solution
By assuming bulb A,B, and C as a group , their effective resistance would be 2 ohms.
Thus, the effective resistance of the circuit is Effective resistance of bulb A,B,C + resistance of Bulb D = 5 ohms
Hence, the current across the circuit is total voltage supplied / effective resistance of the whole circuit = 4/5 A. Therefore, the voltage of bulb D is 4/5A x 3 ohms = 12/5 W

*forgive me for my random attempt , since my teacher never taught me anything about this part

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2. May 26, 2015

### SammyS

Staff Emeritus
The units given in the statement of your problem don't make sense.

What is the problem, word for word, as it was given to you?

3. May 26, 2015

### curiouschris

There is an error here. I think you mean the voltage supplied by the cells is 4 volts

voltage is a measure of the EMF (electromotive force)
w is for watts and it is a measure of energy over time (power) 1 watt = 1 joule for 1 second