$(10$ points$)$ Three situations are given below describing the motion of a charged particle under different conditions. For each case, find the direction of the magnetic force acting on the particle and indicate this direction on the figure.

Answers:

$2.(10$ points$)$ an electron enters a uniform magnetic field of $0\mathrm{.}010$ T directed perpendicular to the field. What is the time taken by the electron for one complete revolution?

Answer: $35\mathrm{.}8{10}^{-10}s$

$3.(10$ points$)$ A point particle charge of $-8C$ moving with velocity of vec$(V)=6$widehat$(k)\frac{m}{s}$ enters a magnetic field region of vec$(B)=3$hat$()-5$hat$()(mT).$ Find the magnetic force acting on the particle in unit vector notation.

Answer: $(-0\mathrm{.}14$hat$()-0\mathrm{.}24$hat$()){10}^{-3}N$