The betatron is designed for fast electrons. It consists of a vacuum chamber, which is placed between the poles of the electromagnet winding is fed with alternating current. The principle of operation is based on the phenomenon of a betatron electromagnetic induction. An alternating magnetic field creates a vortex electric field that accelerates the electrons. Determine what kind of speed the electron acquires at the end of the first round in the betatron, which radius R if the intensity of the uniform magnetic field is changed by H = at the law, where a - constant factor.

Detailed solution with a short recording conditions, laws and formulas used in the decision, the withdrawal of the calculation formula and the answer.
If you have any questions about the decision to write. I try to help.