# Solenoid Ends

*Most recent answer: 02/18/2010*

Q:

Why end field of solenoid is half?

- chetan sharma (age 17)

shimla h.p. india

- chetan sharma (age 17)

shimla h.p. india

A:

Say that in a very long solenoid the field at some internal point very far away from the ends is H. H/2 comes from solenoid on one side of the point, H/2 from the other side. At the end, you've only got one side, so you just get H/2.

Mike W.

Mike W.

*(published on 02/18/2010)*

## Follow-Up #1: solenoid field patterns

Q:

PROVE THAT MAGNETIC FIELD AT THE CENTRE OF THE SOLENOID IS DOUBLE THAT OF AT THE END.

- SOURAV CHANDA (age 19+)

KOLKATA, WEST BENGAL, INDIA

- SOURAV CHANDA (age 19+)

KOLKATA, WEST BENGAL, INDIA

A:

We can't prove that because it isn't exactly true. If you think about putting a solenoid together from two halves, and think about the fields from each half, you'll see why. You'll also be able to see whether the field at the end is more than or less than half the field in the middle.

Mike W.

Mike W.

*(published on 12/03/2011)*