Ohm’s Law & Electrical Power Worksheet
Goal: Find how voltage and resistance set the current in a circuit (V = IR), and how much power the resistor uses (P = VI).
What to do
- Press Reset (12 V, 100 Ω). Record the current and power.
- Press Reset, then “Low resistance”, and record. Repeat with “Higher voltage” and “No voltage”, pressing Reset before each.
- Press Reset and set Resistance to 200 Ω. Record the row. Then also set Voltage to 24 V and record the last row.
Record your results
| Setting | Current | Power |
|---|---|---|
| Default (12 V, 100 Ω) | ||
| Low resistance (12 V, 20 Ω) | ||
| Higher voltage (24 V, 100 Ω) | ||
| No voltage (0 V, 100 Ω) | ||
| 12 V, 200 Ω | ||
| 24 V, 200 Ω |
Questions
What happened to the current when you doubled the voltage from 12 V to 24 V? Use V = IR to explain.
What happened to the current when you doubled the resistance from 100 Ω to 200 Ω?
Doubling the voltage multiplied the power by 4. Explain why, using P = VI.
The 24 V, 200 Ω circuit carries the same current as the default circuit. Does it use the same power?
“Low resistance” draws 0.6 A and uses 7.2 W. Why can a very low resistance be dangerous in real wiring?
Challenge: what resistance would let exactly 0.5 A flow from the 12 V supply? Calculate it, then type it into the lab to check.
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