Ohm's Law — GCSE Physics Revision
Revise Ohm's Law for GCSE Physics. Step-by-step explanation, worked examples, common mistakes and exam-style practice aligned to AQA, Edexcel, OCR, WJEC, Eduqas, CCEA, Cambridge International (CIE), SQA, IB, AP.
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Go to IV CharacteristicsWhat is Ohm's Law?
Ohm's Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature and other physical conditions remain unchanged. This relationship is expressed by the equation V = IR, where V is voltage, I is current, and R is resistance.
Board notes: A key law in all GCSE Physics specifications (AQA, Edexcel, OCR). Understanding which components are ohmic and non-ohmic is crucial.
Step-by-step explanationWorked example
A resistor has a resistance of 12Ω and the potential difference across it is 6V. What is the current flowing through it? Solution: Using Ohm's Law, I = V/R. I = 6V / 12Ω = 0.5A.
Mini lesson for Ohm's Law
1. Understand the core idea
Ohm's Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature and other physical conditions remain unchanged. This relationship is expressed by the equation V = IR, where V is voltage, I is current, and R is resistance.
Can you explain Ohm's Law without copying the notes?
2. Turn it into marks
A resistor has a resistance of 12Ω and the potential difference across it is 6V. What is the current flowing through it?
Underline the method, evidence, or command-word move that would earn credit in GCSE Electricity.
3. Fix the likely mark leak
Watch for this mistake: Applying Ohm's Law to non-ohmic conductors. Ohm's Law only applies to components with a constant resistance, like a resistor at a constant temperature. It does not apply to filament lamps or diodes.
Write one correction rule before doing another practice question.
Practise this topic
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Ohm's Law practice questions
These are original StudyVector questions for revision practice. They are not official exam-board questions.
Question 1
In one GCSE sentence, explain what Ohm's Law is testing.
Answer: Ohm's Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature and other physical conditions remain unchanged. This relationship is expressed by the equation V = IR, where V is voltage, I is current, and R is resistance.
Mark focus: Precise definition and topic focus.
Question 2
A Ohm's Law question uses an unfamiliar context. What should the answer do before adding detail?
Answer: It should name the process, variable, equation, particle model, or evidence being tested, then explain the result using precise scientific vocabulary.
Mark focus: Method selection and command-word control.
Question 3
A student makes this mistake: "Applying Ohm's Law to non-ohmic conductors. Ohm's Law only applies to components with a constant resistance, like a resistor at a constant temperature. It does not apply to filament lamps or diodes." What should their next repair task be?
Answer: Do one Ohm's Law question and review the mistake type.
Mark focus: Error correction and next-step practice.
Ohm's Law flashcards
Core idea
What is the main idea in Ohm's Law?
Ohm's Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature and other physical conditions remain unchanged. This relationship is expre...
Common mistake
What mistake should you avoid in Ohm's Law?
Applying Ohm's Law to non-ohmic conductors. Ohm's Law only applies to components with a constant resistance, like a resistor at a constant temperature.
Practice
What is one useful practice task for Ohm's Law?
Answer one Ohm's Law question and review the mistake type.
Exam board
How should you use board notes for Ohm's Law?
A key law in all GCSE Physics specifications (AQA, Edexcel, OCR). Understanding which components are ohmic and non-ohmic is crucial.
Common mistakes
- 1Applying Ohm's Law to non-ohmic conductors. Ohm's Law only applies to components with a constant resistance, like a resistor at a constant temperature. It does not apply to filament lamps or diodes.
- 2Rearranging the formula incorrectly. A common mistake is to write I = VR or R = VI.
- 3Forgetting the condition that physical conditions (like temperature) must be constant. The resistance of many components changes with temperature.
Ohm's Law exam questions
Exam-style questions for Ohm's Law with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel, OCR, WJEC, Eduqas, CCEA, Cambridge International (CIE), SQA, IB, AP specifications.
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Step-by-step method
Step-by-step explanation
4 steps · Worked method for Ohm's Law
Core concept
Ohm's Law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature and other physical conditions remain unchanged. This rela…
Frequently asked questions
What is an ohmic conductor?
An ohmic conductor is a component that obeys Ohm's Law. Its resistance is constant, so the graph of voltage against current is a straight line through the origin.
What is the relationship between current and voltage in Ohm's Law?
Current is directly proportional to voltage. This means if you double the voltage, you double the current, as long as the resistance stays the same.