Resistance Flashcards – Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028)

What equation relates resistance $R$ to potential difference $V$ and current $I$?

$R = \frac{V}{I}$

What are the units of resistance, potential difference and current?

• Resistance: ohms ($\Omega$)
• Potential difference: volts (V)
• Current: amperes (A)

How can the resistance equation be rearranged to calculate potential difference $V$ or current $I$?

$V = IR$ and $I = \frac{V}{R}$

For what conditions does a resistance calculated from voltage and current apply?

The conditions under which the voltage and current were measured.

With a power supply connected, how should an ammeter and voltmeter be connected to measure a component’s resistance?

Connect the ammeter in series with the component and the voltmeter in parallel across it.

How is resistance in ohms calculated from potential difference in volts and current in amperes?

$R = \frac{V}{I}$

What condition must the current and potential difference readings satisfy when calculating a component’s resistance?

They must refer to the same operating conditions.

How does the length of a metallic wire affect its resistance when material, temperature and cross-sectional area are held constant?

A longer wire has greater resistance.

How does the cross-sectional area of a metallic wire affect its resistance when material, temperature and length are held constant?

A larger cross-sectional area gives lower resistance.