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CAIE IGCSE Physics 4.3.3.2 Action of a variable potential divider

Practise tracing how variable potential dividers control output p.d., lamp brightness and sensor responses in real circuits.

Syllabus
2026–2028
Course
Physics 0625

Exam points

  • explain how an LDR or thermistor changes the share of supply p.d. in a divider
  • predict lamp brightness or voltmeter reading as a slider moves along a resistor
  • select X and Y components to make p.d. across Y rise for a given physical change

4.3.3.2—Action of a variable potential divider question 1

[Maximum number: 3]

Fig. 6.1 shows a circuit which includes an LDR (light-dependent resistor).

Fig. 6.1

Fig. 6.1

The LDR is in a brightly lit room. The voltmeter reads 1.8 V .

The light level in the room changes from bright to dark.

State and explain the effect on the voltmeter reading.
statement
explanation

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