You are Here: Home >< Physics

# June 2010, physics 4 question 11

1. The question is about F=BILsin(theta). There is a wire with a current of 4A, length 0.05m, going through a magnetic field. This is on top of a balance and gives a reading of 0.8 'gram'. It then asks us to calculate the average flux density along the length of the wire.

I went about this by saying that 0.8 grams is 0.8x10^-3 Kg. and that this represents a force of (0.8x10^-3)/9.8 N (using F=mg)

I then substitue everything into F=BIL (It's at right angles) and get '4.08 x10^-4'.
=>
(0.8x10^-3 / 9.8) / (0.05 * 4)

Looking at the markscheme, it just says that it is 0.04T. And i can't see why i am a factor of 100 out.

Please help :/
2. I worked it out in the end. Silly mistake on my part. I quoted F = mg and then in my calculations, and trust me i have no idea why, i did F = m/g. Durrr.

Write a reply… Reply
Submit reply

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
that username has been taken, please choose another Forgotten your password?
2. this can't be left blank
this email is already registered. Forgotten your password?
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
your full birthday is required
1. Oops, you need to agree to our Ts&Cs to register
2. Slide to join now Processing…

Updated: May 20, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### How do I adult!?

What do you wish you'd be taught?

Poll
Useful resources

## Make your revision easier

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.