Define electric potential difference (p.d.) by stating what it means.
In the circuit shown in Fig. 5.1, a power supply, three resistors and a component X are connected together. The power supply has an electromotive force (e.m.f.) of $230\,\text{V}$ and negligible internal resistance. The current in the power supply is $7.0\,\text{A}$.
Identify component X.
Show that the p.d. across the resistor of resistance $0.86\,\Omega$ works out to $6.0\,\text{V}$.
Determine the current $I_1$ in the circuit.
Calculate the p.d. across component X from the circuit.
Calculate the power dissipated in component X from the circuit.
The circuit is intended to supply power to component X. Determine the percentage efficiency of the circuit.
The resistor of resistance $170\,\Omega$ is removed, leaving an open circuit in the lower branch of the circuit. There is no change to the resistance of component X. State whether the current in the power supply increases, decreases or stays the same.
Calculate the p.d. across component X in the circuit.
Calculate the power dissipated in component X from the circuit.
The circuit is intended to supply power to component X. Determine the percentage efficiency of the circuit.
The resistor of resistance $170\,\Omega$ is removed, leaving an open circuit in the lower branch of the circuit. There is no change to the resistance of component X. State whether the current in the power supply increases, decreases or stays the same.