This common misconceptions covers Common Misconceptions within I-V Characteristics for GCSE Physics. Revise I-V Characteristics in Extra Topics for GCSE Physics with 13 exam-style questions and 11 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 8 of 12 in this topic. Use this common misconceptions to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 8 of 12
Practice
13 questions
Recall
11 flashcards
⚠️ Common Misconceptions
Misconception 1: "The gradient of an I-V graph gives resistance"
This is a very common error. The gradient of an I-V graph is I/V, which equals 1/R (not R). To find resistance from an I-V graph, use R = V/I by reading off coordinates at any point, then dividing voltage by current. Steeper gradient = lower resistance (not higher).
Misconception 2: "The filament lamp curve is because current doesn't flow at low voltage"
Even at low voltages, current flows through a filament lamp. The curve through the origin means that some current flows even at tiny voltages. The curve bends because resistance increases as the filament heats up — not because current is blocked at low voltage.
Misconception 3: "A diode doesn't conduct at all in reverse bias"
In practice, a tiny "leakage current" does flow through a diode in reverse bias — it's just so small (microamps) that it's negligible in most circuits. GCSE questions treat the reverse resistance as infinite and reverse current as zero, which is a reasonable simplification.
Misconception 4: "You can put the ammeter in parallel"
An ammeter must always be in series with the component it is measuring current through. Placing it in parallel would short-circuit the component and potentially damage the ammeter (ammeters have very low resistance). The voltmeter goes in parallel.