P.3.5.1.2 Current-voltage characteristics

Which is the current–voltage characteristic graph for a filament lamp up to its working voltage?

• A

• B

• C

• D

The graph shows how the potential difference V across an electrical component varies with current I in the component.

A tangent has been drawn on the curve at point P for a current of I₂.

What is the resistance of the electrical component when the current in the component is I₂?

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• 
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In the circuit below, the potential difference across the light emitting diode (LED) is 1.8 V when it is emitting light.

The current in the circuit is 20 mA. What is the value of the resistor R?

• 80 Ω

• 90 Ω

• 150 Ω

• 160 Ω

The graph shows the current–voltage (I–V) characteristics of a filament lamp.

What is the resistance of the filament when the potential difference (pd) across it is 4.0 V?

• 500 Ω

• 1700 Ω

• 2000 Ω

• 6000 Ω

A resistor and diode are connected in series with a variable power supply as shown in the diagram.

Which best shows the characteristic for the combination of the resistor and diode?

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• 
• 
• 

The 12 V battery in the circuit shown has negligible internal resistance. The diodes have 'ideal' characteristics.

The current through the battery is approximately

• 0 A

• 0.10 A

• 0.20 A

• 0.40 A