Question 1: Define an electromagnet and explain how it differs from a permanent magnet.

Answer: An electromagnet is a magnet created by passing an electric current through a coil of wire, producing a magnetic field. Unlike a permanent magnet, its magnetic field can be turned on or off by controlling the current.

Question 2: Describe the main components required to construct an electromagnet.

Answer: A coil of wire, a power supply (battery), and a core material such as iron to concentrate the magnetic field.

Question 1: Calculate the magnetic field strength (B) at the centre of a solenoid with 500 turns, a length of 0.5 m, carrying a current of 2 A. Use the formula B = μ₀ * (N/L) * I, where μ₀ = 4π × 10⁻⁷ T·m/A.

Answer: B = 4π × 10⁻⁷ * (500 / 0.5) * 2 = approximately 2.51 × 10⁻³ T

Question 2: If the number of turns in a coil is doubled while keeping the current and length constant, how does the magnetic field strength change? Explain your answer.

Answer: The magnetic field strength doubles because B is directly proportional to the number of turns N.

Question 1: List three variables that can be adjusted to increase the strength of an electromagnet. Describe the effect of each variable.

Answer: Increasing the current increases magnetic field strength; increasing the number of turns in the coil strengthens the field; using a ferromagnetic core like iron concentrates the magnetic flux and enhances the magnetic field.

Question 2: Describe two safety precautions that should be taken when constructing or operating an electromagnet.

Answer: Ensure the current is not too high to prevent overheating, and avoid touching the coil while the current is flowing to prevent burns.

Question 1: A student notices that increasing the current in an electromagnet's coil causes the magnetic effect to become stronger. Explain why this occurs, using scientific principles.

Answer: Increasing the current increases the flow of electrons through the coil, which in turn strengthens the magnetic field around the coil due to more moving charges generating a larger magnetic flux, thus making the electromagnet's effect stronger.

Question 2: An industry uses electromagnets to sort scrap metal. The electromagnets are turned on and off repeatedly. Explain the advantages of this method.

Answer: Turning electromagnets on and off allows selective attraction and release of metal objects, improving sorting efficiency. It also reduces energy consumption and prevents overheating by controlling the magnetic field as needed.

Question 1: A solenoid has 800 turns, a length of 0.4 m, and carries a current of 3 A. Calculate the magnetic field strength at the centre of the solenoid. Use μ₀ = 4π × 10⁻⁷ T·m/A.

Answer: B = 4π × 10⁻⁷ * (800 / 0.4) * 3 = approximately 6.00 × 10⁻³ T

Question 1: Describe how electromagnets are used in electric bells and the advantages they provide over mechanical solutions.

Answer: Electromagnets in electric bells attract a striker to hit the bell when current flows, producing sound. They are faster, more reliable, and can be controlled electrically, unlike mechanical solutions that rely on physical parts.

Question 2: Explain the role of electromagnets in MRI (Magnetic Resonance Imaging) machines.

Answer: Electromagnets generate strong, uniform magnetic fields in MRI machines, aligning hydrogen nuclei in the body. Radio waves then disturb this alignment, and the electromagnets help detect signals to create detailed images.