# Experienced magnetic field

1. Jan 30, 2016

### jyotirmaya ojha

Lets say you have an electromagnet which produces some magnetic field when current is passed through it . Now there is some magnetic field in its surrounding then it is expected to exert some torque according to the formula torque=magnetic moment*magnetic field .Now my question is :
will the magnetic field used in this formula be just of the surrounding or the net vector addition of surrounding magnetic field and its own magnetic field ?

2. Jan 31, 2016

### Wee-Lamm

Would it matter if the polarity of the 2 fields were in opposition?

3. Jan 31, 2016

### marcusl

Just the external field.

4. Jan 31, 2016

### Wee-Lamm

Is the original magnetic field ignored entirely?
If so then, what would be the effect of increasing or decreasing the current being passed through the original magnet?

5. Jan 31, 2016

### marcusl

The torque depends on the the external field, on the effective magnetic dipole moment of the electromagnet, and on their relative directions. If the magnet geometry is such that it has a moment, then increasing the current increases the moment.

6. Jan 31, 2016

### Wee-Lamm

For my own clarity, Torque is a measure of the twisting force being applied against the Electromagnetic field, from the external magnet, at the magnetic moment?

Better?

Edit: to replace pressure with twisting force

Last edited: Jan 31, 2016
7. Jan 31, 2016

### marcusl

Torque is not a pressure, it is a twisting force or moment.

8. Feb 1, 2016

Yes

9. Feb 1, 2016

### Wee-Lamm

Thank you. :-)