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Power dissipated by a resistor HTML5


The circuit is made up of a variable power supply, a variable resistor R and, a light bulb all connected in series.
An ammeter, placed in series, allows the current, I, to be measured.  A voltmeter connected in parallel with the resistor, R, allows the voltage across the resistor VR to be measured.
The light bulb acts like a resistor, RA, with resistance equal to 10Ω.
The curve shows the power dissipated in the the resistor.  The unit of power is the Watt (W).
P = VR x I = R x I2

  • When the voltage is increased, the current, I, increases and the power dissipated by the resistor, R, increases.
  • When the value of the resistor is increased, I decreases and the power dissipated by the resistor, R, decreases.

The variable resistor, R, allows control of the current intensity in the circuit.

Slide the cursor on the voltage and/or resistance tab to establish the desired values.

Learning goals

  • To know the relationships between power (P), voltage (V) and current intensity (I).
  • To understand that resistance allows for the control of current intensity and therefore the power dissipated in a circuit.

Learn more

The power dissipated by a resistance varies with the square of the current passing through it. The curve P = f(I) is a parabola.

The light bulb placed in series in the circuit will visually…

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