1. A metal sphere of radius 4 m holds a total charge of +0.8 nC. What is the electric potential at the center of the sphere? (in V)

2. Two particles with the same mass but different charges are accelerated from rest through a potential difference of 200 V. The final speed of the first particle is 2.1 times larger than the final speed of the second particle. How many times larger is the charge on the first particle as compared to the charge on the second particle?

3. If the magnetic field that passes perpendicular through a single wire loop is increased from from 0.2 T to 1.0 T within a time of 0.1 s, the induced emf in the wire loop is 5 V. How large is the area of the wire loop? (in m²)

4. Light of wavelength 360 nm needs 500 seconds to travel from our Sun to Earth. How much time (in seconds) needs light of twice that wavelength for the same travel?

5. At what distance away from a 100-W lightbulb is the intensity of its emitted light equal to the intensity of a 400-W lightbulb observed from a distance of 80 m. (in m)

6. Unpolarized light is sent through two polarizers whose transmission axes are at an angle of degrees with respect to each other. You measure the intensity of the light after passing through the two polarizers. For = 0 degrees you observe an intensity of 1 W/m². For = 90 degrees you observe that no light passes through. How would you have to choose the angle so that light passes through the two polarizers with an intensity of 0.5 W/m²? 60 degrees 75 degrees 45 degrees 15 degrees 30 degrees

7. The speed of light in a certain medium is 1.9 x 10⁸ m/s. What is the index of refraction in this medium?

8. A little known fact is that both Robinson Crusoe and Friday wore eyeglasses. As it so happens, Robinson Crusoe was nearsighted, while Friday was farsighted. Whose eyeglasses did they use whenever they wanted to start a fire by focusing the sun's rays?

Friday's. Both actually worked, but Robinson Crusoe's was a little better. Both would work equally well. Neither worked. Robinson Crusoe's.