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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 V_{R} to be measured.

The light bulb acts like a resistor, R_{A}, with resistance equal to 10Ω.

The curve shows the power dissipated in the the resistor. The unit of power is the Watt (W).

P = V_{R} x I = R x I^{2}

- 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.

- 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.

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…