State Faraday’s laws of electromagnetic induction and Lenz’s law. Prove theoretically, the relation between e.m.f. induced and rate of change of magnetic flux in a coil moving in a uniform magnetic field. A circular coil of 250 turns and diameter 18 cm carries a current of 12 A. What is the magnitude of magnetic moment moment associated with the coil?
Answers
Explanation:
calculate the boiling point of solution when 2 gram of Na2So4(MM142g/mol) was dissolved in 50g of water assuming complete ionization kb of water=0.52kkg per mol.
Answer:
1.) Faraday’s law of electromagnetic induction, also known as Faraday’s law is the basic law of electromagnetism which help us predict how a magnetic field would interact with an electric circuit to produce an electromotive force (EMF). This phenomenon is known as electromagnetic induction.
Faraday’s Laws of Electromagnetic Induction consists of two laws. The first law describes the induction of emf in a conductor and the second law quantifies the emf produced in the conductor.
i.) Whenever a conductor is placed in a varying magnetic field, an electromotive force is induced. If the conductor circuit is closed, a current is induced which is called induced current.
ii.) The induced emf in a coil is equal to the rate of change of flux linkage.
Lenz's law states that when the magnetic flux associated with a coil is changed, the emf induced in the coil is in a direction which tries to oppose the change of flux.
2.) When we pull out the coil, the flux in it reduces. Hence the current generated will be such that it'll try to increase the flux. In order to increase the flux, it has to produce flux in the same direction as the field. By right hand rule, this direction should be in the clockwise sense. Hence the induced current is as shown in the diagram by the arrows.
Flemming's left hand rule states that when the thumb, the index-finger and the middle-finger of your left hand are held mutually perpendicular to each other, then the thumb shows the force acting in a straight conductor carrying current in the direction of the middle-finger placed in a magnetic field in the direction of the index-finger. You can remember this as FBI. Thumb F, index-finger B and middle-finger I.
As per this rule, forces f, f1 and f2
will act on the coil in directions as shown in the diagram. The f1 and f2 will cancel each other and the only unbalanced force is f acting towards left. When we pull the coil towards right, we have to do work against this force.
If we apply equal and opposite force, then the work done by the force acting on the coil is negative.
3.) We know that,
r = D / 2 = 18/2 = 9 cm = 0.09 m
M = NiA = 250 × 12 × π × (0.09)^2 =
= 76.30 A - m^2