20)in this diagram, medium a represents water and medium b represents air. the phenomenon in this diagram, moving from a to b, is called
a) diffraction.
b) dispersion.
c) refraction.
d) resolution.

21)if you put a straw into a glass of water, the straw looks to be bent, although nothing has physically happened to the straw. the term that describes this property of light is
a) absorption.
eliminate
b) diffraction.
c) reflection.
d) refraction.

22)as we move through the visible spectrum, red to violet (right to left in the image), the wavelength and the frequency
a) increases; decreases
b) increases; increases
c) decreases; increases
d) decreases; decreases

23)according to the electromagnetic spectrum, gamma rays have the shortest wavelength. therefore, gamma rays have frequency.
a) a random
b) the lowest
c) the highest
d) an undetermined

24)an echo is an example of sound wave
a) diffraction.
b) interference.
c) reflection.
d) refraction.

25)why does light refract when it encounters the glass in a lens?
a) because it speeds up, which causes it to bend
b) because it slows down, which causes it to bend
c) because it hits a dense medium, which causes it to bounce off
d) because it gets absorbed, which causes it to lessen in intensity