JC · H1/H2 Physics Round 1/6 Score 0

🔎 Divider Detective

Investigate a real cell and design a sensor potential divider.

Cell investigation

Current 0.00 A
Terminal p.d. 0.00 V
V = E − Ir Intercept = E Gradient = −r Vout = Vs × Rbottom Rtop + Rbottom
A loaded cell loses p.d. internally; a divider shares p.d.

Investigation controls

Live terminal characteristic

The physics

Real cell: E = V + Ir. E and V are measured in volts, I in amperes and internal resistance r in ohms.

With load R: I = E/(R + r), and V = IR.

The V–I graph is straight: intercept E; gradient −r (V/A = Ω).

Potential divider: Vout = Vs × Rbottom/(Rtop + Rbottom).

An LDR's resistance decreases as light increases. An NTC thermistor's resistance decreases as temperature increases.