# Magnetic field and Relativity

1. Nov 20, 2009

### IPhO' 2008

We can use B = $$\frac{\mu}{4\pi}$$ $$\frac{q[vr]}{r3}$$
when v << c (c is a speed of light) but if v is nearly to c we can't use this formula.
What is a formula when v is nearly to c.

2. Nov 20, 2009

### IPhO' 2008

r3[/SUP ] is r3

3. Nov 20, 2009

### Staff: Mentor

4. Nov 20, 2009

Thank you.