The human eye is sensitive to light with wavelength up to 750 nm. What is the frequency of radiation at this wavelength? (1 nm = 10-9 m and c = 3.00 108 m/s)
a. 8.5 108 Hz
c. 4.0 1014 Hz
b. 1.8 108 Hz
d. 7.7 1014 Hz
Question 2
As a train starts from rest and then accelerates down the track, coming toward me faster and faster, the speed of the sound waves coming toward me will be:
a. slower than the normal speed of sound in air.
b. equal to the normal speed of sound in air.
c. some constant speed faster than the normal speed of sound in air.
d. faster and faster.