# What Magnetic field is generated

1. Apr 16, 2013

If am using a flat spiral coil and giving sinusoidal voltage signal to it. i want to find the field generated at a point which is located at d cms from the flat spiral coil how can i get it? and also if am using another flat spiral coil at distance d cms what is the voltage induced in it..?

2. Apr 16, 2013

### Staff: Mentor

3. Apr 16, 2013

Thank you DaleSpam,

Actually i thought of it but had doubt whether we can use it or not, if it is correct method to proceed or not..

4. Apr 16, 2013

### Staff: Mentor

The Biot-Savart law is an approximation for the magnetostatic case. Strictly speaking, your coil is not magnetostatic, but as long as the size of the coil divided by c is small relative to the period of your voltage then the approximation is fine.

5. Apr 16, 2013

Am confused little bit what do you mean when you are telling coil divided by c.. can you explain it clearly...

6. Apr 16, 2013

### Staff: Mentor

Suppose your coil is 1 m in diameter. 1 m / (299792458 m/s) = 3.3 ns So if the period of your sinusoidal voltage is much greater than 3.3 ns (i.e. frequency much < 300 MHz) then the approximation should be fine.

Last edited: Apr 16, 2013
7. Apr 16, 2013

Yeah understood but the coil which am going to use will be 8cms, for that case we approximation will be fine nah

8. Apr 16, 2013

### Staff: Mentor

Yes, in that case you should be OK to use Biot-Savart up to 900 MHz or so.

9. Apr 16, 2013