The exhibition opens in 45 minutes. Half the school just went dark.
You are the student volunteer with the physics department's multimeter. Nobody will tell you the answers. You have a small parts drawer, your physics, and 45 minutes. What can you do with what you have?
6:59 PM · the doors open
Ohm's law
V = I × R
Series
R total = R₁ + R₂ + … · same current everywhere · voltage is shared
Parallel
Same voltage across every branch · branch currents add up
Power
P = V × I
Real batteries
V terminal = EMF − I × r (r = internal resistance)