Name:_______________________

Quiz 8

12/15/2004

Ch. 24-26

Useful number(s): speed of light c=3x10⁸ m/s

1) A good antenna can be made from a wire that is one-quarter of the wavelength of the EM wave that it is supposed to receive. How long would a quarter-wavelength antenna be for your favorite radio station (be sure to tell me which station is your favorite)? If you don’t have a favorite you can use mine 91.5MHz.

2) A laser beam in air hits a flat piece of glass (n=1.5) at an angle of 25 deg to the normal. The refracted beam continues through the glass and enters water (n=1.3). What is the exiting angle into the water?

3) A 180cm man stands 4m away from a mirror with a focal length of –3m. His feet are on the principle axis.

a) Draw a diagram including at least 2 rays that begin at the man’s head.

b) Is the mirror convex or concave? What is the mirror’s radius of curvature?

c) How far is the image from the mirror? Is it real or virtual? Is it upright or inverted? How tall is the image?