1. A lamp with a 60W bulb is plugged into a 120v outlet. a)What are the rms and peak currents through the lamp? b)What is the bulb’s resistance? but requires a value for R I rms =60W/120v = 0.5 A whileso In fact, notice the peak voltage now 60W = (0.5 A) 2 R R = 240 

2. Several minutes after being switched on, which of the above light bulbs will be noticeably brighter? 1) A 2) B 3) both the same

3. When plugged into an active household outlet, which of the light bulbs above will be brighter? 1) A 2) B 3) both the same

4. Which of the light bulbs above will be brighter? Hint: remember there is a self-induced voltage across the coil. 1) A 2) B 3) both the same Voltage drop across coil is V = L  I /  t. Loop rule:voltage drop across bulb A is less Brightness:P = V 2 / R With a simple DC battery connected, a few minutes after turn-on, there is no longer a changing current (having achieved steady state at maximum I=V/R) so the inductor (though it moderated the current surge at power-up, does nothing. Both bulbs burn equally bright.