The wavelength of sodium yellow light in air is 589 nm.
(a)
We can take the speed of light in air as ‘c’ = 3.00 * 10^8 m/s.
Given wavelength (λar) = 589 * 10^-9 m
Find the frequency (f)
Using the relationship:
c=f
frequency = c / λar = (3.00 * 10^8) / (5.89 * 10^-7)
frequency=5.09*10^14Hz
(bus transport:
(λglass) / (λair) = (ηair) / (ηglass) = 1 / 1.55
λglass = (5.89 * 10^-7 / 1.55) = 3.80 * 10^-7 m = 380 nm
(c) wave speed on glass = f * λglass
glass = (5.09 * 10^14 Hz) * (3.80 * 10^-7 m)
vglass = 1.94 * 10^8 m/s