Phya4 elec induction

Help with 3ai. Im guessing you use tge right hand rule right?

Posted from TSR Mobile

Yes, the RH Rule.
Field direction is given and the motion of the rod is given. You need to find the direction of the induced emf.

So if its east to west, then the second finger is to the left? And the first finger is up. But the directiot of tge induced emf involves lenz so if its dropped down, doesnt that mean the emf direction is up so north?

Theres no answers given for these questions

Posted from TSR Mobile

The rod is dropped so the motion is down. (Thumb)
The field is south to north so if you are sitting facing north your first finger points away from you.
Twist your arm a bit and what is the direction of your 2nd finger. East is on your right and west on your left now. This finger will give you the direction of the (positive) induced emf.

Ohh I get it now. It said to find the velocity so I got confused. So if tge current is moving from west to east, that means all the electrons are moving west right? So the positive end is tge east?

Posted from TSR Mobile

I assumed from your question about the RH rule you meant the question part asking for the induced emf. The motion of the rod is just downwards of course. (1st part of question.)
So if motion is down and field points away from you, induced positive conventional current or emf is to your right, which is East.
So yes positive to the east.

So whenever we are dealing with electrons, we use the right hand rule right? Im guessing thats not true since for a current carrying wire its tge LH rule. I dont get when you are meantvto use whichever rule. It says rh is for generators but that metal rod isnt really a generator...

Posted from TSR Mobile

The LH and RH rules don't deal with electrons.
The RH rule and LH rule are based on "conventional" current, which is always the flow of positive charge. (The rules date back to the time before the electron was discovered!)
If you want to know the direction of flow of electrons or negative charges you just take the opposite direction to that of the positive charge.
The LH rule is used for working out the direction of the force on a conductor carrying a current in a magnetic field. For this reason it is often called the "motor" rule.
The RH rule is used for finding the direction of the induced emf (and current if it can flow) when a conductor is moved through a magnetic field. Because it deals with the creation of emf and possibly current it is often called the "generator" or "dynamo" rule.
You are quite right that the rod could hardly be described as a generator in this situation. The point is that there is an emf generated in it, so you use the RH rule. Agreed, this emf is not of much use because there is no circuit for the current to flow in, but that is beside the point.