Worksheet Chapter 3: Electricity

1. A light bulb is labelled '12 V, 24 W'. It is connected to a power supply and operates continuously for 10 minutes at rated capacity. (a) Calculate the resistance of the bulb filament. (b) Calculate the total electric charge passed through the bulb during the 10 minutes. (c) Calculate the number of electrons passing through the bulb filament during this duration.

2. True or False: The electromotive force (e.m.f.) of a cell is measured across its terminals when current is flowing through a closed circuit.

3. True or False: Connecting dry cells in parallel increases the total electromotive force (e.m.f.) available to the circuit.

4. Which equation correctly represents the relationship between electromotive force (E), terminal potential difference (V), current (I), and internal resistance (r)?

5. An experiment is conducted using a cell, variable resistor, ammeter, and voltmeter. The linear graph of V against I gives a y-intercept of 3.0 V and a negative slope gradient of -1.2 V A⁻¹. (a) State the electromotive force (e.m.f.) of the cell. (b) Determine the internal resistance (r) of the cell. (c) Calculate the maximum short-circuit current that the cell can supply.

6. A nichrome resistance wire has a length of 2.0 m and a cross-sectional area of 5.0 × 10⁻⁷ m². The resistivity of nichrome is 1.1 × 10⁻⁶ Ω m. (a) Calculate the resistance of the nichrome wire. (b) If a potential difference of 4.4 V is applied across the wire, calculate the current flowing through it.

7. Fill in the blank: The SI unit for electrical resistivity is ________.

8. A circuit consists of two resistors, R1 = 6 Ω and R2 = 12 Ω, connected in parallel across a battery with e.m.f. 12 V and negligible internal resistance. (a) Calculate the effective resistance of the parallel combination. (b) Calculate the main total current drawn from the battery. (c) Calculate the power dissipated in the R1 (6 Ω) resistor.

9. A battery with e.m.f. E = 6.0 V and internal resistance r = 0.8 Ω is connected to a resistor R = 11.2 Ω. (a) Calculate the total resistance of the circuit. (b) Calculate the current flowing through the circuit. (c) Calculate the terminal potential difference across the battery.

10. An electric water heater is rated '240 V, 3000 W'. It is used to heat water for 45 minutes each day. (a) Calculate the electrical current drawn by the heater. (b) Calculate the energy consumed in kilowatt-hours (kWh) in one day. (c) If electricity costs RM 0.30 per kWh (unit), calculate the cost of operating the heater for 30 days.