Question 1: Resistors are components used to limit the flow of current in a circuit. When connected in series, resistors are arranged end-to-end, and the total resistance increases. In parallel, resistors are connected across the same two points, and the total resistance decreases. Understanding how to calculate total resistance in both configurations is essential for designing safe and efficient electrical systems.

Answer: Resistors in series add directly to give total resistance (R_total = R1 + R2 + ...). In parallel, the reciprocal of the total resistance is the sum of the reciprocals of each resistor (1/R_total = 1/R1 + 1/R2 + ...).

Question 1: Define a resistor in an electrical circuit.

Answer: A resistor is a component that limits or regulates the flow of electrical current in a circuit.

Question 2: Explain the main difference between resistors connected in series and in parallel.

Answer: In series, resistors are connected end-to-end so the current flows through each resistor sequentially, increasing total resistance. In parallel, resistors are connected across the same two points, reducing the overall resistance.

Question 3: Why does the total resistance decrease when resistors are connected in parallel?

Answer: Because in parallel, multiple pathways allow current to flow, reducing the overall resistance as the equivalent resistance is less than any individual resistor.

Question 1: Calculate the total resistance when three resistors of 4Ω, 6Ω, and 8Ω are connected in series.

Answer: R_total = 4Ω + 6Ω + 8Ω = 18Ω

Question 2: Calculate the total resistance when the same resistors (4Ω, 6Ω, 8Ω) are connected in parallel. Use the formula 1/R_total = 1/R1 + 1/R2 + 1/R3.

Answer: 1/R_total = 1/4 + 1/6 + 1/8 = 0.25 + 0.1667 + 0.125 = 0.5417; R_total ≈ 1 / 0.5417 ≈ 1.846Ω

Question 1: Describe an experiment to measure the total resistance of resistors connected in parallel. Include variables to control and safety precautions.

Answer: Set up a circuit with known voltage and connect resistors in parallel across the power supply. Measure the current flowing through the circuit using an ammeter. Vary the resistance values or number of resistors and record the current each time. Calculate total resistance using R = V/I. Control variables include voltage and resistor temperature; safety precautions involve ensuring connections are secure and power is switched off when adjusting components.

Question 2: In a parallel circuit with two resistors of 10Ω and 20Ω, if the voltage across both resistors is 12V, what is the total current supplied by the power source?

Answer: Current through R1 = V/R1 = 12V/10Ω = 1.2A; through R2 = 12V/20Ω = 0.6A; total current I_total = 1.2A + 0.6A = 1.8A

Question 1: Describe a practical example of where resistors in parallel are used in electronic devices.

Answer: Resistors in parallel are used in power supplies to distribute current evenly and reduce overall resistance, such as in voltage dividers or LED lighting circuits.

Question 2: How does understanding resistor configurations help in designing safer electrical circuits for household appliances?

Answer: It allows engineers to control current flow, prevent overheating, and ensure devices operate within safe voltage and current limits by selecting appropriate resistor arrangements.