SPM: Induced Current

ok.lets continue our discussion on Electromagnetic induction..
In SPM syllabus, its important 4 u to know how to determine the direction of induced current in the following cases:
i. direction of induced current in a straight wire..
u can use Flemming's right hand rule to identify the induced current's direction.
BUT remember!!!!!! we use RIGHT hand for this..NEVER use your left hand!!! Left hand is used to find the FORCE in electromagnet. We use RIGHT hand to find the CURRENT direction..and its only valid for induction. How to use this rule?? look at the diagram below

One student asked me..Sir..i'm confused ..whats the difference between left & right hand rule???
OK, to answer that question.. please notice the following comparison carefully,

Electromagnet	Electromagnetic Induction
- Use FLEMMING LEFT HAND	- Use FLEMMING RIGHT HAND
- current is needed	- Motion/force is needed
-FORCE is produced	-INDUCE CURRENT is produced
- process of making a temporary magnet	- process to generate induced EMF to generate induce current
- concept used to build D.C motor	- used to build Generator

ii.direction of induced current in solenoid
for this case u really need to understand the whole concept carefully..student always get confuse when using this law...
Ok..to determine the current direction in solenoid..we use LENZ's law. What is LENZ's law???

Lenz's law states that...
the direction of induce current is such that the change producing it will beopposed.
*******please understand this law & try to memorize it*********


Lets now apply what actually this law trying to tell us. Observe the following figure 1 & figure 2.

In figure 1:
- the NORTH pole of the bar magnet is moving into the coil,

According to Lenz's law..
- the induced current produced will flow in such a way to oppose the approaching bar magnet
- thus, the flowing induce current produces North pole on the end of coil as to repel the
approaching magnet.


In figure 2:
the NORTH pole of the bar magnet is pulled out from the coil,

According to Lenz's law..
- the induced current produced will flow in such a way that it won't allow the bar magnet leaving
the coil
- thus, the flowing induce current produces SOUTH pole on the end of coil as to prevent the
magnet from leaving.