State Kirchhoff’s first law.
A battery is connected to two resistors X and Y, as shown in Fig. 6.1. Resistor X has a greater resistance than resistor Y. State and explain which resistor dissipates more power.
The two resistors are made from wires of equal length. The wires are both made from metal with the same resistivity. State and explain which resistor is made from wire with the larger cross-sectional area.
A battery of electromotive force (e.m.f.) $9.0\,\text{V}$ and negligible internal resistance is connected in series with a light-dependent resistor (LDR) and a fixed resistor of resistance $1800\,\Omega$, as shown in Fig. 6.2. A voltmeter is connected across the fixed resistor. The voltmeter reads $5.4\,\text{V}$. Calculate the current in the circuit.
Calculate the resistance $R_L$ of the LDR.
The light intensity on the LDR increases. With reference to the current in the circuit, state and explain what happens, if anything, to the voltmeter reading.