Year 11 / Electrical circuits
Charge flows. Energy transfers.
Current is charge passing a cross-section per unit time. Potential difference is energy transferred per unit charge. Conventional current is defined in the direction positive charge would move; conduction electrons in a metal drift in the opposite direction.
An ohmic component has constant resistance at constant temperature and follows V = IR. A straight V-versus-I line through the origin has gradient R. Heating can change resistance and make a real component non-ohmic.
An ohmic circuit
Explore the relationship
Ideal DC supply and a resistor at constant temperature. Dots show conventional current, not electron motion.
Current / A
Tap or focus a plotted point to read its values.
View plotted data as a table
| Series | Supply voltage / V | Current / A |
|---|---|---|
| Current / A | 0 | 0 |
| Current / A | 0.2 | 0.02 |
| Current / A | 0.4 | 0.04 |
| Current / A | 0.6 | 0.06 |
| Current / A | 0.8 | 0.08 |
| Current / A | 1 | 0.1 |
| Current / A | 1.2 | 0.12 |
| Current / A | 1.4 | 0.14 |
| Current / A | 1.6 | 0.16 |
| Current / A | 1.8 | 0.18 |
| Current / A | 2 | 0.2 |
| Current / A | 2.2 | 0.22 |
| Current / A | 2.4 | 0.24 |
| Current / A | 2.6 | 0.26 |
| Current / A | 2.8 | 0.28 |
| Current / A | 3 | 0.3 |
| Current / A | 3.2 | 0.32 |
| Current / A | 3.4 | 0.34 |
| Current / A | 3.6 | 0.36 |
| Current / A | 3.8 | 0.38 |
| Current / A | 4 | 0.4 |
| Current / A | 4.2 | 0.42 |
| Current / A | 4.4 | 0.44 |
| Current / A | 4.6 | 0.46 |
| Current / A | 4.8 | 0.48 |
| Current / A | 5 | 0.5 |
| Current / A | 5.2 | 0.52 |
| Current / A | 5.4 | 0.54 |
| Current / A | 5.6 | 0.56 |
| Current / A | 5.8 | 0.58 |
| Current / A | 6 | 0.6 |
| Current / A | 6.2 | 0.62 |
| Current / A | 6.4 | 0.64 |
| Current / A | 6.6 | 0.66 |
| Current / A | 6.8 | 0.68 |
| Current / A | 7 | 0.7 |
| Current / A | 7.2 | 0.72 |
| Current / A | 7.4 | 0.74 |
| Current / A | 7.6 | 0.76 |
| Current / A | 7.8 | 0.78 |
| Current / A | 8 | 0.8 |
| Current / A | 8.2 | 0.82 |
| Current / A | 8.4 | 0.84 |
| Current / A | 8.6 | 0.86 |
| Current / A | 8.8 | 0.88 |
| Current / A | 9 | 0.9 |
| Current / A | 9.2 | 0.92 |
| Current / A | 9.4 | 0.94 |
| Current / A | 9.6 | 0.96 |
| Current / A | 9.8 | 0.98 |
| Current / A | 10 | 1 |
| Current / A | 10.2 | 1.02 |
| Current / A | 10.4 | 1.04 |
| Current / A | 10.6 | 1.06 |
| Current / A | 10.8 | 1.08 |
| Current / A | 11 | 1.1 |
| Current / A | 11.2 | 1.12 |
| Current / A | 11.4 | 1.14 |
| Current / A | 11.6 | 1.16 |
| Current / A | 11.8 | 1.18 |
| Current / A | 12 | 1.2 |
Explore: Raise the resistance at fixed voltage. Watch the current and particle drift change.
A resistor carries 0.30 A at 6.0 V.
- R = V/I = .
- R = 20 Ω.
Assumed knowledge
Charge in coulombs.
Learning checkpoints & source
YOUR LEARNING CHECKPOINT- Distinguish current, potential difference and resistance.
- Interpret current–voltage measurements.
READY TO TRY IT?