Current, potential difference and resistance — WJEC GCSE Physics
In summary: Current, potential difference and resistance is a key topic in WJEC GCSE Physics. Key exam tip: Always check the units in calculations and convert to SI units if necessary
Exam Tips for Current, potential difference and resistance
- Always check the units in calculations and convert to SI units if necessary
- When describing I-V characteristics, clearly distinguish between linear and non-linear components
- Use the correct circuit symbols for diodes, thermistors, and LDRs in diagrams
- Remember that power equations can be combined; choose the one that fits the known variables
Common Mistakes
- Confusing the units for charge (Coulombs), current (Amperes), and potential difference (Volts)
- Assuming resistance remains constant for all components, particularly lamps
- Incorrectly rearranging the V = IR or P = IV equations
- Failing to recognize that current is constant in a single closed loop
Marking Points
- Current is the rate of flow of charge (Q = It)
- A source of potential difference and a closed circuit are required for charge to flow
- Current has the same value at any point in a single closed loop
- Relationship between potential difference, current, and resistance (V = IR)
- Power transfer equations (P = IV, P = I²R, P = E/t)
- Energy transferred equations (E = QV, E = Pt)
- Variation of resistance in components like lamps, diodes, thermistors, and LDRs
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