1. Frequency: [tex]7.06\cdot 10^{14} Hz[/tex]
The frequency of a light wave is given by:
[tex]f=\frac{c}{\lambda}[/tex]
where
[tex]c=3\cdot 10^{-8} m/s[/tex] is the speed of light
[tex]\lambda[/tex] is the wavelength of the wave
In this problem, we have light with wavelength
[tex]\lambda=425 nm=425\cdot 10^{-9} m[/tex]
Substituting into the equation, we find the frequency:
[tex]f=\frac{c}{\lambda}=\frac{3\cdot 10^{-8} m/s}{425\cdot 10^{-9} m}=7.06\cdot 10^{14} Hz[/tex]
2. Period: [tex]1.42 \cdot 10^{-15}s[/tex]
The period of a wave is equal to the reciprocal of the frequency:
[tex]T=\frac{1}{f}[/tex]
The frequency of this light wave is [tex]7.06\cdot 10^{14} Hz[/tex] (found in the previous exercise), so the period is:
[tex]T=\frac{1}{f}=\frac{1}{7.06\cdot 10^{14} Hz}=1.42\cdot 10^{-15} s[/tex]
