(Solved): answer 4 1. (10 points) A current produce a magnetic field of magnitude 5T at distance 0.03m fro ...

1. (10 points) A current produce a magnetic field of magnitude $5\mu \mathrm{T}$ at distance $0.03\mathrm{m}$ from a long, straight wire. What is the distance from the wire with this current where the magnitude of the magnetic field is $2\mu \mathrm{T}$ ? 2. (10 points) An electron is accelerated through $2400\mathrm{V}$ from rest and then enters a region where is a uniform 1.7 T magnetic field perpendicularly to it. What is the magnitude of magnetic force on the electron and the radius of the path? 3. (10 points) Flexible circular loop shown in Fig. 1 has a radius, $-5\mathrm{cm}$ and is in a magnetic field of strength $0.2\mathrm{T}$ which is perpendicular to the plane. During the time 0.5 s the loop is grasped at points $A$ and $B$ and stretched until its area is nearly zero. Find the average induced emf in the loop during that time and the current through the loop if its resistance is $2\Omega$. 4. ( 10 points). Find the direction of the force on a positive charge for each diagram shown in Fig. 2, where $\mathrm{v}$ is the velocity of the charge and $\mathrm{B}$ is the direction of the magnetic field. ( $\otimes$ means the vector points inward. $\odot$ means it points outward, toward you.)