Simple circuits

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Question 43
Medium

A student investigates the current–potential difference characteristics of a light-emitting diode (LED).

Fig. 1.1 shows the circuit diagram the student sets up to measure the current in the LED and the potential difference across the LED.

Fig. 1.1

Fig. 1.1: Circuit diagram with mistakes

a.

The student has made two mistakes when setting up the circuit.

Identify the two mistakes and explain how to correct them.

Mistake 1: Correction 1: Mistake 2: Correction 2:

[4]
b.

The student corrects the circuit and records the current for different values of the potential difference. Fig. 1.2 shows a graph of their results.

Fig. 1.2

Fig. 1.2: I-V characteristic graph of the LED

State the potential difference when the LED starts to conduct.

[1]
c.

Use the gradient of the graph to calculate a value for the resistance of the LED when it is conducting.

[4]

Simple circuits Questions

  1. GCSE
  2. /Physics
  3. /Simple circuits