a) Explain the origin of magnetic fields in terms of moving charges. [3]

b) A straight wire carries a current of 5 A. Calculate the magnetic field strength at a distance of 2 cm from the wire. [3]

a) Describe the representation of magnetic fields using field lines. [3]

b) A solenoid has 100 turns and carries a current of 0.5 A. If the length of the solenoid is 20 cm, calculate the magnetic field strength inside the solenoid. [3]

a) Define electromagnetic induction. [3]

b) A coil with 200 turns is placed in a magnetic field that changes at a rate of 0.02 T/s. Calculate the induced EMF in the coil. [3]

a) Describe how the magnetic field due to a current-carrying conductor varies with distance from the conductor. [3]

b) A coil with 150 turns has a radius of 10 cm. If a magnetic field of 0.05 T is applied perpendicular to the plane of the coil, calculate the magnetic flux through the coil. [3]

c) If the magnetic field in part b) decreases to zero in 2 seconds, determine the induced EMF in the coil. [4]

a) Explain the principle behind electromagnetic induction in terms of Faraday's and Lenz's laws. [3]

b) A straight wire 1 m long moves at a speed of 2 m/s perpendicular to a magnetic field of 0.1 T. Calculate the induced EMF in the wire. [3]

c) How would the induced EMF change if the wire moved parallel to the magnetic field? [2]

a) Differentiate between the magnetic field produced by a solenoid and a single loop of wire carrying the same current. [3]

b) A solenoid of length 30 cm has 300 turns and carries a current of 1 A. Calculate the magnetic field strength inside the solenoid. [3]

c) How would the magnetic field strength change if the number of turns was doubled, but the current was halved? [3]

a) Describe the factors that affect the resistivity of a material. [3]

b) A wire has a resistance of 5 ohms at 20°C. If its temperature coefficient of resistance is 0.004/°C, calculate its resistance at 50°C. [3]

c) How does the drift velocity of electrons in a conductor relate to the current flowing through it? [3]

a) Describe the origin of magnetic fields in terms of moving charges. [3]

b) A straight conductor of length 2 m carries a current of 3 A. If it is placed in a magnetic field of strength 0.5 T at an angle of 30° to the field, calculate the magnetic force acting on it. [3]

c) If the same conductor is shaped into a loop, how would the net magnetic force on it change when placed in the same magnetic field? [2]

d) Explain why transformers only work with alternating current (AC) and not direct current (DC). [3]

a) Explain the significance of the right-hand rule in determining the direction of the magnetic field due to a current-carrying conductor. [3]

b) A solenoid has a length of 40 cm and consists of 400 turns. If it carries a current of 2 A, calculate the magnetic field strength inside the solenoid. [4]

c) Describe the effect on the magnetic field strength if the solenoid is filled with a ferromagnetic material. [3]

d) How does the magnetic field due to a solenoid compare with that of a bar magnet? [3]

a) Define electromagnetic induction. [2]

b) A coil with 500 turns and a cross-sectional area of 0.02 m^2 is placed in a magnetic field that changes from 0.1 T to 0.5 T in 0.5 seconds. Calculate the induced EMF in the coil. [4]

c) State Lenz's law and explain its significance in the context of energy conservation. [3]

d) How does the principle of electromagnetic induction find application in electric generators? [3]