Solve Resistance Question: Find R of Resistor with 60W Lamp & 120V

[arod2812]

Homework Statement

A 60-W lamp is placed in series with a resistor and a 120-V source. If the voltage across the lamp is 35-V, what is the resistance (R) of the resistor?

Homework Equations

I am pretty sure I am using the right equation, but I am not getting the right answer. What am I doing wrong?

The Attempt at a Solution

P=IV --> 60W=I(120V) --> I=-.50 A
R=V/I --> (120V-35V)/.5A = 170 ohms (this is what I calculated but it isn't the right answer)

 

[rock.freak667]

Voltage across the lamp is 35V, so that in P=VI,V=35 for the lamp.

Current through the lamp = P/V =60/35

 

[chroot]

A lamp rated as 60W would dissipate 60W when connected directly to the 120V supply -- when you add a resistor in series with it, it no longer dissipates 60W.

- Warren