Question 1: Transformers are devices that transfer electrical energy between two or more circuits through electromagnetic induction, primarily used to change voltage levels in power systems.

Answer: Transformers transfer electrical energy via electromagnetic induction to change voltage levels.

Question 2: What are the main components of a transformer?

Answer: Primary coil, secondary coil, core

Question 1: Explain how a changing current in the primary coil induces a voltage in the secondary coil.

Answer: A changing current in the primary coil creates a changing magnetic field in the core, which induces a voltage in the secondary coil through electromagnetic induction.

Question 2: What role does the iron core play in a transformer?

Answer: It concentrates and guides the magnetic flux, increasing the efficiency of induction.

Question 1: A transformer has 500 turns on the primary coil and 100 turns on the secondary coil. If the primary voltage is 240 V, what is the secondary voltage?

Answer: Secondary voltage = (Number of secondary turns / Number of primary turns) × Primary voltage = (100 / 500) × 240 V = 48 V

Question 2: Calculate the turns ratio if a transformer steps down voltage from 240 V to 48 V.

Answer: Turns ratio = Primary turns / Secondary turns = 240 V / 48 V = 5:1

Question 1: Describe an experiment to demonstrate how a transformer changes voltage levels. Include variables to control and safety precautions.

Answer: An experiment can involve connecting a primary coil to an AC power source and measuring the voltage on the secondary coil with a voltmeter. Variables to control include the number of turns in coils and the input voltage. Safety precautions include ensuring proper insulation, avoiding contact with live wires, and using a fuse or circuit breaker.

Question 2: Why are transformers not used to step up or step down DC voltages?

Answer: Transformers only work with alternating current because they rely on changing magnetic fields to induce voltage.

Question 1: A power transformer reduces the voltage from 11,000 V to 230 V for household supply. If the primary current is 50 A, what is the approximate secondary current assuming ideal conditions?

Answer: Using power conservation: Primary power = Secondary power; Vp × Ip = Vs × Is; 11,000 V × 50 A = 230 V × Is; Is = (11,000 × 50) / 230 ≈ 2391 A

Question 2: Explain how the efficiency of a transformer affects its real-world application in power distribution.

Answer: Transformer efficiency determines how much electrical energy is lost as heat during voltage conversion. Higher efficiency means less energy wasted, making power transmission more economical and reliable. In real-world applications, efficiencies above 95% are desired to minimise energy loss over long distances.