1. ## frequencies

13) Sound vibrations with frequencies greater than 20,000 Hz are called?
a)infrasonics
b)supersonics
c)ultrasonics
d)megasonics

14) The lowest tone to resonate in an open pipe of length L is 400 Hz. what is the frequency of the lowest tone that will resonate in a closed pipe of length 2L.
a)100Hz
b)0.800kHz
c)200Hz
d)1.60kHz

15) For certain angles, TOTAL INTERNAL REFLECTION can occur when light tries to pass from one medium to another which has.
a)a larger index of refraction
b)a smaller index of refraction
c)an index of refraction which is sin(45 degrees)
d)an index of refraction which is sin-1(Θ)
e)the same index of refraction

16) A ray of light, which is traveling in air, is incident on a glass plate at a 45 degrees angle. The most we can say about the angle of refraction in the glass.
a) is less than 45 degrees
b)is equal to 45 degrees
c)is unknown because it all depends on the index of refraction of glass
d)is greater than 45 degrees

17) An index of refraction less than one for a medium would imply that.
a)the speed of light in the medium is greater than the speed of light in vacuum.
b)the speed of light in the medium is the same as the speed of light in vacuum.
c)refraction is not possible
d)reflection is not possible

18) which of the following materials has the slowest speed of light?
a)water
b)oil
c)air
d)flint glass

2. Originally Posted by twistedmexican
13) Sound vibrations with frequencies greater than 20,000 Hz are called?

c)ultrasonics

14) The lowest tone to resonate in an open pipe of length L is 400 Hz. what is the frequency of the lowest tone that will resonate in a closed pipe of length 2L.

c)200Hz

15) For certain angles, TOTAL INTERNAL REFLECTION can occur when light tries to pass from one medium to another which has.

b)a smaller index of refraction

16) A ray of light, which is traveling in air, is incident on a glass plate at a 45 degrees angle. The most we can say about the angle of refraction in the glass.
a) is less than 45 degrees

17) An index of refraction less than one for a medium would imply that.
a)the speed of light in the medium is greater than the speed of light in vacuum.

18) which of the following materials has the slowest speed of light?

d)flint glass
Hello,

1. Use the definitions.
2. Use a table of values.
3. I have removed the answers which are wrong (as far as I can judge it)

to #18:

The oil isn't specified and the only reference I have is: Kassia-oil n = 1.604. There are a lot of different sorts of flint glass: F3 n = 1.61279 or SF4 n = 1.75496.
Nevertheless both sorts of flint glass have a higher refraction index than the oil and therefore will cause the slowest speed of light.