# Electromagnetic Induction

1.) Okay I have this problems but I can't get the picture or show the picture so i will describe it. I have two loops or circles next to each other. The first loop is continuous and there are no breaks in the loop. So it looks just like a circle. The second loop has a break in it and it also has a emf or power supply then it is a break in the circle or loop (like an open gate) then the loop continues. The current is flowing from positive to negative in a clockwise motion.

Here is the question:

Suppose you are looking at two loops in the plane of the page as shown. When the switch is thrown closed in the left hand coil, what is: a) the direction of the induced current in the other loop; b) the situation after a "long" time; c) the direction of induced current in the second loop if the second loop is quickly pulled horizontally to the right?

2.) What is the inductive reactance? (write down an expression and specify it units)

Okay i know that it is xL=wL and the units are ohms but please explain how do you derive this! and explain what it is use for!

#### Solution Preview

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SOLUTION

Fundamentals in a nutshell

1. When current flows through a conductor, an electromagnetic field is produced around it. The direction of the magnetic lines of force thus produced can be determined using the right hand rule as follows :

Curl the fingers of right hand with the thumb stretched out in the direction of the current flow. Then the fingers point in the direction of the magnetic field lines.

Fingers

(field line direction)

Thumb (Current direction)

2. Faraday's law : Whenever the amount of magnetic flux (total number of magnetic lines) linked with a circuit changes, an emf is induced in the circuit. The induced emf lasts so long as the change in magnetic flux continues. The magnitude of emf induced in the circuit is directly proportional to the rate of change of the magnetic flux linked with the circuit.

Thus the magnitude of induced emf e = dφ/dt (rate of change of flux)

3. Lenz's law : While the magnitude of the induced emf is given by Faraday's law, the polarity of the induced emf is given by Lenz's law. According to this law, the polarity of the induced emf will be such ...

#### Solution Summary

Step by step solution provided. Electromagnetic induction problems are examined.