# phy 108 questions 9

Homework problems: Chapters 15-16

- Suppose that water waves have a wavelength of 2.4 m and a period of 0.5 seconds. Whatâ€™s the velocity of these water waves?
- A sound wave has a velocity of 334 m/s and a frequency of 400 Hz. Whatâ€™s the wavelength of the sound? What type of waves are sound waves?
- Two waves propagate from different directions on the same rope. Suppose they have the same amplitude 0.2 m. Whatâ€™s the possible maximum and minimum fluctuation of the rope, respectively?
- The tension force on a string is 80 N. The mass of the string is 0.1 kg and the length is 0.5 m. What will be speed of waves produced on the string?
- An orange light has a frequency of 6×10
^{14}Hz. Whatâ€™s its wavelength? What type of waves are light waves? - Please list all known electromagnetic waves in order of frequency from highest to lowest.
- What is electromagnetic induction and what are its applications?

Homework problems: Chapter 17

- A laser beam reaches surface of a glass block with an incident angle of 45â°.

1) Please draw a schematic diagram to show reflection ray and refraction ray.

2) If glass has an index of refraction of 1.5, whatâ€™s the speed of light in glass. - A converging lens has a focus length of 10 cm. A pencil stands on its optic axis with a distance of 15 cm from the lens.

a) Please draw three principal rays to find the image of the pencil;

b) Whatâ€™s the image distance?

c) Is it magnified? Is the image inverted? - A concave mirror has a focal length of 10 cm. Please draw two principal rays to find the image of a pencil standing 15 cm away from it.