Question 1: Define a magnetic field in your own words.

Answer: A magnetic field is a region around a magnetic material or a moving electric charge within which the force of magnetism acts.

Question 2: Explain how the magnetic field lines around a bar magnet are arranged and what this indicates about the field.

Answer: The magnetic field lines emerge from the north pole and enter the south pole, forming continuous loops. The density of the lines indicates the strength of the magnetic field.

Question 3: Describe the mechanism by which a current-carrying wire produces a magnetic field.

Answer: A current flowing through a wire produces a magnetic field around it due to the movement of charged particles, with the field forming concentric circles around the wire.

Question 1: Calculate the magnetic force on a 0.5 A current-carrying wire that is 0.3 m long and placed perpendicular to a magnetic field of strength 0.2 T. Use the formula F = BILsinθ, where θ = 90°. Provide your answer in newtons (N).

Answer: F = 0.2 T × 0.5 A × 0.3 m × sin(90°) = 0.2 × 0.5 × 0.3 × 1 = 0.03 N

Question 2: A solenoid with 200 turns and a length of 0.5 m carries a current of 2 A. Calculate the magnetic field strength inside the solenoid using B = μ₀ × (N/L) × I. Assume μ₀ = 4π × 10⁻⁷ T·m/A.

Answer: B = 4π × 10⁻⁷ T·m/A × (200 / 0.5 m) × 2 A = 4π × 10⁻⁷ × 400 × 2 = approximately 1.005 × 10⁻³ T

Question 1: Describe a simple experiment to demonstrate the magnetic field pattern around a bar magnet. Include the variables involved and safety precautions.

Answer: An experiment involves placing iron filings on a piece of paper over a bar magnet to visualise the magnetic field lines. Variables include the type of magnet, distance from the magnet, and the material of the filings. Safety precautions include handling the magnet carefully to avoid pinching fingers and ensuring the area is free of ferromagnetic objects to prevent accidents.

Question 2: Identify the independent, dependent, and control variables in an experiment to measure the magnetic field strength along the axis of a solenoid.

Answer: Independent variable: position along the solenoid axis; Dependent variable: magnetic field strength; Control variables: current in the solenoid, temperature, and type of wire used.

Question 1: A researcher measures the magnetic field strength at various distances from a small magnet and records the following data: at 2 cm, B = 0.05 T; at 4 cm, B = 0.025 T. Explain how the magnetic field strength relates to distance and state what this suggests about the nature of magnetic fields.

Answer: The magnetic field strength decreases as the distance from the magnet increases, approximately following an inverse square law. This suggests that magnetic fields weaken with distance, and the field lines spread out as they move away from the magnet.

Question 1: Explain how magnetic fields are utilised in the operation of an MRI (Magnetic Resonance Imaging) scanner.

Answer: MRI scanners use strong, uniform magnetic fields to align hydrogen nuclei in the body. Radiofrequency pulses then disturb this alignment, and the nuclei emit signals as they realign, which are used to produce detailed images of internal tissues.

Question 2: Describe one technological application that relies on the principles of magnetic fields and explain its significance.

Answer: Electric motors use magnetic fields to convert electrical energy into mechanical energy. They operate by interactions between magnetic fields in the stator and rotor, producing torque. This technology is essential in appliances, transportation, and industrial machinery, making modern life more efficient.