Posted by Elizabeth on .
A series circuit contains only a resistor and an inductor. The voltage V of the generator is fixed. If R = 10 Ω and L = 4.2 mH, find the frequency at which the current is onehalf its value at zero frequency?
Answer in Hz

Physics 
bobpursley,
when is
2*10=sqrt(100+2PIfL)
solve for f