What are the four interactions of electromagnetism stated in the theory of electromagnetism? Use details to support your answer.

QUESTION 2 (a) With the aid of diagrams, differentiate linear polarization from circular polarization. (b) Derive the general equation for electromagnetic wave from Maxwell's equations. (c) A bar magnet is moved rapidly toward a 40-turn circular coil of wire. As the magnet moves, the average value of Bcose over the area of the coil increase from 0.0125T to 0.45 T in 0.250 s. If the radius of the coils is 3.05 cm, and the resistance of its wire is 3.55 2, find the magnitude of (a) the induced emf and (b) the induced current.

3. When an object enters an electric field, it will feel a force. How is the amount of force felt determined?

There are both series and parallel circuits in your house. A circuit breaker is a safety feature in all houses. How do the circuit breakers work, and what could happen if houses did not have circuit breakers. Use details to support your answer.

. A circular coil of radius a with N turns lies in the xy plane with the z axis through itscentre, as shown in Fig. 1. The magnetic field along the axis is given by: B(z)=\frac{\mu_{0} N I a^{2}}{2\left(a^{2}+z^{2}\right)^{3 / 2}} :0.20 A, andN =5.0 x 10-Am2 lies along the z axis at a distance of zwhere I is the current. The coil has a =1.0 cm, I =1000. A magneticdipole with magnitude m =+5.0 cm from the centre of the coil. The dipole points along the +z axis. (a) What is the torque on the dipole? (b) What is the magnetic energy of the dipole? (c) What is the force on the dipole? (Hint: make the approximation z? > a².) Byconsidering the coil as a dipole, and making the analogy with bar-magnet dipoles,explain the sign of the force on the dipole. (d) Sketch the dipole's magnetic energy as a function of z, and describe its motion, as-suming that it is free to move without any frictional forces. (Hint: make an analogywith a ball rolling on a curved surface, and apply conservation of energy.) (e) The dipole has a mass of 7.9 x 10-6 kg. What is its maximum speed? (f) The dipole is made of ferromagnetic iron, which has a relative atomic mass of 55.8.Calculate the average dipole moment per iron atom along the z axis in units of theBohr magneton, UB. Explain how this value can be significantly less than uB, eventhough each individual iron atom has a dipole moment of - pg.

4. What is the cause of the Northern Lights, also known as the Aurora Borealis?