1. How does the brightness of the refracted ray change when theincident angle (from glass to air) changes from less than criticalangle to greater than critical angle?

a. brighter

b. dimmer

c. unchanged

d. dimmer and then disappear

2. Trying to picture an electroscope you made in the lab, onrubbing an rubber rod with fur, the electrons from the fur gettransferred to the rubber rod. While holding the rubber rod nearthe electroscope (not touching the top paper clip), the foil leavesseparate. At the same time, someone rubs a Styrofoam cup on a pieceof cloth and also brings it to the electroscope, the leaves close abit. What is the type of charge the Styrofoam cup carrying?

A. positive

b. negative

c. cannot decide

3. What would be the correct description of how an image in aplane mirror compares to the original object?

a.		The image is reflected left to right
b.		The image is reflected front to back
c.		The image is reflected both front to back and left to right
d.		The sense of the image changes depending on the angle ofincidence
e.		It depends on the original object

4. If the distance between the object and the screen is 1meter,a thin lens is put in between and moving, when the lens is 30 cmaway from the object, a clear image is formed on the screen. Howmuch is the focal length of this thin lens?

a. 0.048 m

b. 21 cm

c. 0.019 m

d. 52.5