Question 1: A solenoid is a long coil of wire wrapped in many turns, which produces a magnetic field when an electric current passes through it. The magnetic field inside a solenoid is similar to that of a bar magnet.

Answer: A coil of wire that produces a magnetic field when current flows through it

Question 2: Explain why increasing the number of turns in a solenoid increases its magnetic field strength.

Answer: Because the magnetic field strength is proportional to the number of turns and increasing turns increases the overall magnetic flux.

Question 1: What is the primary purpose of a solenoid in electrical devices?

Answer: To generate a controlled magnetic field for switching, sensing, or actuating.

Question 2: Describe how the magnetic field inside a solenoid varies along its length.

Answer: The magnetic field is strongest at the centre and relatively uniform inside, decreasing rapidly outside.

Question 1: A solenoid has 500 turns, a length of 0.5 metres, and carries a current of 2 A. Calculate the magnetic field strength inside the solenoid using the formula B = μ₀ * (N / L) * I, where μ₀ = 4π × 10⁻⁷ T·m/A.

Answer: B = 4π × 10⁻⁷ × (500 / 0.5) × 2 ≈ 2.51 × 10⁻³ Tesla

Question 2: If the number of turns in a solenoid is doubled, and all other factors remain constant, what will be the effect on the magnetic field strength?

Answer: The magnetic field strength will double.

Question 1: Design a simple experiment to measure how the magnetic field strength varies with the current in a solenoid. Include key variables and safety precautions.

Answer: Students can set up a solenoid with a power supply, an ammeter, and a magnetic field sensor or compass at a fixed point inside the solenoid. Variables include current (independent) and magnetic field strength (dependent). Safety precautions include ensuring the current does not exceed safe limits to prevent overheating and avoiding contact with live wires.

Question 2: Identify three key variables that affect the magnetic field produced by a solenoid and explain how each influences the field.

Answer: Number of turns (more turns increase the magnetic field), current (higher current increases the field), and length of the solenoid (longer length decreases the field strength at a given point).

Question 1: A student records the magnetic field strength inside a solenoid at different currents: 0.5 A (1.26 × 10⁻³ T), 1 A (2.52 × 10⁻³ T), 1.5 A (3.78 × 10⁻³ T). Describe the relationship between current and magnetic field strength based on this data.

Answer: The magnetic field strength increases proportionally with the current, indicating a direct linear relationship.

Question 1: Explain how solenoids are used in electric relays and the advantages they offer in controlling circuits.

Answer: Solenoids in relays act as electromagnetic switches. When current flows through the solenoid, it creates a magnetic field that moves a switch contact, opening or closing a circuit. Advantages include remote operation, fast switching, and the ability to control high currents with low currents.

Question 2: Describe a real-world application of solenoids in industry or technology and discuss its importance.

Answer: Solenoids are used in automotive starter motors to engage the engine; they are crucial for reliable engine starting and automation in machinery.