Charge, Current, Fields and Voltage
Relate charge flow to current, recognise AC and DC evidence and interpret electric fields and voltage.
How to study National 5 Physics
Move from a physical situation to a model, relationship, calculation and evidence-based conclusion, while using current official documents for exact assessment conditions.
Core concepts
Concept 1
Current is charge transferred per unit time, expressed by Q = It.
Exam cue: Convert microamps or milliamps before using Q = It.
Concept 2
Direct current keeps one direction while alternating current repeatedly changes direction and can be recognised on a trace.
Exam cue: Inspect whether a trace crosses zero to identify direction reversal.
Concept 3
A charged particle experiences force in an electric field, and supply voltage measures energy transferred per unit charge.
Exam cue: Use field direction and charge sign to predict force direction.
Risk pitfalls and guardrails
Treating charge as used up in a component.
Guardrail: Check the model, assumptions, prefixes, units, significant figures and whether every conclusion is supported by evidence.
Calling a varying but always positive trace alternating current.
Guardrail: Check the model, assumptions, prefixes, units, significant figures and whether every conclusion is supported by evidence.
Forgetting that a negative charge accelerates opposite to field direction.
Guardrail: Choose a direction convention and distinguish signed vector quantities from scalar magnitudes.
Memory anchors
Current
Charge transferred per unit time.
Charge relationship
Q = It.
DC
Charge flow remains in one direction.
AC
Charge flow repeatedly reverses direction.
Electric field
A charged particle experiences a force.
Voltage
Energy transferred per unit charge.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which description gives the rate measured by an ammeter?
How much charge passes when 3.0 A is maintained for 20 s?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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