Two electrons are very far apart and travel toward each other. Each is traveling with a speed of 2.55 x 10^5 m/s. Since the electrons repel each other they slow to a stop before moving away from each other. What is the distance of closest approach?

3.90 10^_9 m

7.80 10^-9 m

8.83 10^-5 m

6.24 10^-5 m

If you are looking in the end of a solenoid and observe the current going around the solenoid in the counter-clockwise direction, the magnetic field _______

points into the solenoid.

points out of the solenoid.

is circular in the clockwise direction.

is circular in the counterclockwise direction.

An electron with a speed v perpendicular to a magnetic field B experiences a force F that causes it to move along a circular path of radius r. If the speed of the electron is doubled, the new radius is

0.5 r

still r

2r

4r