Question 1: Define voltage, current, and resistance in an electrical circuit.

Answer: Voltage is the potential difference between two points, current is the flow of electric charge, and resistance is the opposition to current flow.

Question 2: Explain why the total voltage across resistors in series is the sum of individual voltages.

Answer: Because in series, the voltage divides among resistors proportionally to their resistance, and the total voltage is the sum of these voltages.

Question 1: A circuit has three resistors of 10 Ω, 20 Ω, and 30 Ω connected in series. Calculate the total resistance R_total.

Answer: R_total = 10 + 20 + 30 = 60 Ω

Question 2: In a parallel circuit, two resistors of 15 Ω and 30 Ω are connected across a 12 V supply. Calculate the total resistance R_total.

Answer: 1/R_total = 1/15 + 1/30 = 2/30 + 1/30 = 3/30; R_total = 30/3 = 10 Ω

Question 1: Describe a safe procedure to measure the current in a circuit with a series resistor setup.

Answer: Connect an ammeter in series with the resistor, ensure the circuit is powered off before connecting, then turn on the power and record the current reading.

Question 2: Identify two variables that could affect the resistance of a resistor in a circuit and explain how.

Answer: Temperature and material composition; increasing temperature can increase resistance in some materials, while the material type determines the inherent resistance.

Question 1: A series circuit has a total voltage of 12 V across three resistors of 4 Ω, 6 Ω, and 8 Ω. Describe how the voltage is distributed across each resistor.

Answer: The voltage divides proportionally to resistance; the resistor with higher resistance drops a larger voltage, calculated using V = IR for each resistor.

Question 2: In a parallel circuit, if the total current supplied is 3 A and the resistors are 10 Ω and 20 Ω, what is the current through each resistor?

Answer: Using I = V/R, first find V across each resistor: V = IR; total voltage V = IR_total, where R_total = (1/10 + 1/20)^-1 = 6.67 Ω. V = I × R_total = 3 × 6.67 ≈ 20 V. Then, current through 10 Ω resistor: I = V/R = 20/10 = 2 A; through 20 Ω resistor: I = 20/20 = 1 A.

Question 1: Explain how understanding the rules for voltage and current in parallel circuits is important in the design of household electrical wiring.

Answer: In household wiring, parallel circuits allow multiple appliances to operate independently; understanding V/I/R ensures safe voltage distribution and current flow, preventing overloads and ensuring reliability.

Question 2: Describe how the principles of series and parallel resistance are applied in designing electronic devices like smartphones or computers.

Answer: Designers use series and parallel resistances to control current flow, manage heat dissipation, and optimise power efficiency within compact circuits. Parallel arrangements allow multiple components to receive the required voltage, while series components can be used for current limiting or voltage dividing, ensuring device safety and functionality.