Idea 6of 7Builds onCoil it up
The right hand reads it
Which end of the coil is north, and how to tell?
Today you'll discover
- a hand that reads the field's direction
- what happens to north when the current reverses
- why the rule needs conventional current
Think firstNorth is on the right. Reverse the current
The current through the coil is reversed. What happens to the north end?
Decide first, then press Next. Watch the thumb flip with the current.
A coil with current arrows and a straight field inside it, north marked at the right. After a prediction, a right hand appears beneath the coil with the fingers curled along the current and the thumb pointing along the field; the current is then reversed and the thumb and the north end flip. The last step asks the field's shape round a straight wire.
See the whole ideathe big idea and the key word, in one place
The big idea
Fingers with the current, thumb along the field.
Easy to get wrongUse conventional current, positive to negative, with the RIGHT hand. Mixing in electron flow gives every field exactly backwards.
Key word
- right-hand rule
- with the right hand, fingers curled along the conventional current give the thumb along the coil's field; or thumb along a straight current gives fingers along its circular field
About this modelConventional current, right hand: fingers with the current, thumb along the field inside. Reverse I and N swaps ends.
Conventional current, right hand: fingers with the current, thumb along the field inside. Reverse I and N swaps ends.
Ready to use it?
- Use the right-hand rule to find a coil's north end or a straight wire's field direction.