Mistake Master
Mistake Master · AP Physics C: E&M · Unit 11 · Step-Through Animation
Whose Volts Are In Your Formula?
You'll learnto compute the power in one element from values that element actually owns, to rank bulb brightness by recomputing rather than counting, and to keep watts and watt-hours apart.
Ask for the power in a 4 ohm resistor and the fastest route uses the battery's 12 volts, which gives 36 watts. The true answer is 4 watts, nine times smaller, because that resistor only ever sees 4 of the 12 volts. Every symbol in a power formula has to belong to the same element. Twelve short steps; press Next for each one.
every symbol from the same element · energy is power times time
Before you start
What you're looking at
A 12 V battery driving two unequal resistors, so a value borrowed from the wrong element gives a visibly wrong answer.
The question
Which voltage goes into the power formula for one element, and what decides how brightly a bulb glows?
Step 1 / 12