Homework
1. Which band of the electromagnetic spectrum has a. the lowest frequency? b. the
shortest wavelength? 2. Which of the following electromagnetic waves has the highest
frequency? a. radio b. ultraviolet radiation c. blue light d. infrared radiation 3. Why can
light be used to measure distances accurately? What must be known in order to make
distance measurements? 4. Shortwave radio is
oadcast between 3.50 and 29.7 MHz.
To what range of wavelengths does this co
espond? Why do you suppose this part of
the spectrum is called shortwave radio? 5. The compound eyes of bees and othe
insects are highly sensitive to light in the ultraviolet portion of the spectrum, particularly
light with frequencies between 7.5 × 1014 Hz and 1.0 × 1015 Hz. To what wavelengths
do these frequencies co
esponds? Flat Mi
ors: 1. For each of the objects listed below,
identify whether light is reflected diffusely or specularly. a. a concrete driveway b. an
undistu
ed pond c. a polished silver tray d. a sheet of paper e. a mercury column in a
thermometer 2. f you are stranded on an island, where would you align a mi
or to use
sunlight to signal a searching aircraft? 3. If you are standing 2 m in front of a flat mi
or,
how far behind the mi
or is your image? What is the magnification of the image? 4.
When you shine a flashlight across a room, you see the beam of light on the wall. Why
do you not see the light in the air? 5. A flat mi
or that is 0.85 m tall is attached to a wall
so that its upper edge is 1.7 m above the floor. Use the law of reflection and a ray
diagram to determine if this mi
or will show a person who is 1.7 m tall his or he
complete reflection.
1. A concave makeup mi
or is designed so that a person 25.0 cm in front of it sees an
upright image at a distance of 50.0 cm behind the mi
or. What is the radius of curvature
of the mi
or? What is the magnification of the image? Is the image real or virtual? 2. A
pen placed 11.0 cm from a concave spherical mi
or produces a real image 13.2 cm
from the mi
or. What is the focal length of the mi
or? What is the magnification of the
image? If the pen is placed 27.0 cm from the mi
or, what is the new position of the
image? What is the magnification of the new image? Is the new image real or virtual?
Draw ray diagrams to confirm your results. 3. If an object is placed outside the focal
length of a concave mi
or, which type of image will be formed? Will it appear in front of
or behind the mi
or? Convex Mi
or 4. A spherical glass ornament is 6.00 cm in
diameter. If an object is placed 10.5 cm away from the ornament, where will its image
form? What is the magnification? Is the image virtual or real? Is the image inverted o
upright? 5. A convex mi
or forms an image from a real object. Can the image ever be
larger than the object?
1. If you stick a piece of transparent tape on your desk and then quickly pull it off,
you will find that the tape is attracted to other areas of your desk that are not charged.
Why does this happen? 2. Metals, such as copper and silver, can become charged by
induction, while plastic materials cannot. Explain why. 3. Why is an electrostatic spray
gun more efficient than an ordinary spray gun? Electric Forces (Coulomb’s Law) 4.
What are some similarities between the electric force and the gravitational force? What
are some differences between the two forces? 5. A small glass ball ru
ed with silk
gains a charge of +2.0 x 10-6 C. The glass ball is placed 12 cm from a small charged
u
er ball that ca
ies a charge of −3.5 x 10-6 C. (kC = 8.99 × 109 N•m2/C2). Use
Coulomb’s Law equation. a. What is the magnitude of the electric force between the two
alls? b. Is this force attractive or repulsive? c. How many electrons has the glass ball
lost in the ru
ing process?