Ohm's Law Lab

Light up two bulbs, then change the battery and the bulbs to see how voltage, current and resistance are connected.

How are the bulbs connected?
Voltage
3.0 V
Total resistance
12.00 Ω
Current
0.25 A
Bulb power (1 / 2)
0.4 W / 0.4 W

The maths, live

Series R = R₁ + R₂R = 6 + 6 = 12.00 Ω
Ohm's law I = V ÷ RI = 3.0 ÷ 12.00 = 0.25 A
Power P = I² × RP₁ = 0.25² × 6 = 0.4 W

Which way are the bulbs brighter: series or parallel? Why?

How it works

A battery pushes electric charge around a circuit. The push is the voltage (V), the flow of charge is the current (I) and anything that slows the flow down is resistance (R). Ohm's law connects them: V = I × R.

In a series circuit the bulbs are in one loop, so their resistances add up and the same current flows through both. In a parallel circuit each bulb has its own path to the battery, so each one gets the full voltage.

Try this

  1. Are two bulbs brighter in series or in parallel?
  2. Double the battery voltage. What happens to the current?
  3. In parallel, make one bulb's resistance much bigger. Does the other bulb change?