10.2 CHAPTER 10. COLOUR
wavelength λ.
λ =
c
f
=
3 × 108
490 × 1012
= 6. 122 × 10 −7 m
= 612× 10 −^9 m
= 612 nm
Therefore the orange light has a wavelength of 612 nm.
Example 3: Frequency of Green
QUESTION
The wavelength of greenlight ranges between 500 nm an d 565 nm. Calculate
the range of frequenciesthat correspond to this range of wavelengths.
SOLUTION
Step 1 : Determine how to approach the problem
Use
c = f× λ
to determine f.
Step 2 : Calculate frequency corresponding to upper limit of wavelength
range
c = f× λ
f =
c
λ
=
3 × 108 m· s−^1
565 × 10 −^9 m
= 5, 31 × 1014 Hz
Step 3 : Calculate frequency corresponding to lower limit of wavelength
range