So I thought I had a handle on the right hand rule for determining the direction of the magnetic field inside a solenoid however after a few textbook questions I am now unsure. The rule I have been taught is to curl your fingers in the direction of the current and your thumb will point to the north pole of the solenoid. Below is the solution to one of the examples (The distance $d$ and point $A$ can be ignored, this was for a second part to the question).
So, for the solenoid on the left, our fingers curl around from the back of the bar to the front, and our thumb is pointing to the right. But as apparent, it should be point to the left. Similarly, for the solenoid on the right, our fingers curl around the bar in an anti-clockwise motion and our thumb points upwards, once again contradicting the solution. So is the rule I have been taught incorrect? Am I applying it incorrectly?
Best Answer
I think the diagram in your book might be wrong.
The right hand rule or Maxwell's corkscrew rule tells us to point our thumb in the direction of the current, and thus wrapping our fingers will show us the flow of the magnetic field.
Thus, pointing my thumb upwards(along the direction of current at the left start of the solenoid) will cause my fingers to curl into the solenoid, which is the direction of magnetic field in a solenoid equivalent to the magnetic field inside a bar magnet as it goes from South to North. A correct image is shown here.
This means that the poles should be switched from what's shown in your book.