(a) [tex]4.74\cdot 10^14 Hz[/tex]
The frequency of an electromagnetic wave is given by:
[tex]f=\frac{c}{\lambda}[/tex]
where
[tex]c=3.0\cdot 10^8 m/s[/tex] is the speed of the wave in a vacuum (speed of light)
[tex]\lambda[/tex] is the wavelength
In this problem, we have laser light with wavelength
[tex]\lambda=632.8 nm=6.33\cdot 10^{-7} m[/tex]. Substituting into the formula, we find its frequency:
[tex]f=\frac{3.0\cdot 10^8 m/s}{6.33\cdot 10^{-7} m}=4.74\cdot 10^14 Hz[/tex]
(b) 427.6 nm
The wavelength of an electromagnetic wave in a medium is given by:
[tex]\lambda=\frac{\lambda_0}{n}[/tex]
where
[tex]\lambda_0[/tex] is the original wavelength in a vacuum (approximately equal to that in air)
[tex]n[/tex] is the index of refraction of the medium
In this problem, we have
[tex]\lambda_0=632.8 nm[/tex]
n = 1.48 (index of refraction of glass)
Substituting into the formula,
[tex]\lambda=\frac{632.8 nm}{1.48}=427.6 nm[/tex]
(c) [tex]2.03\cdot 10^8 m/s[/tex]
The speed of an electromagnetic wave in a medium is
[tex]v=\frac{c}{n}[/tex]
where c is the speed of light in a vacuum and n is the refractive index of the medium.
Since in this problem n=1.48, we find
[tex]v=\frac{3\cdot 10^8 m/s}{1.48}=2.03\cdot 10^8 m/s[/tex]
