Final answer:
The apparent shift in the color of the light is due to the Doppler effect. The light appears yellow because your motion towards it has compressed the wavelength towards the blue end of the visible spectrum. If the light had actually been yellow, it would have appeared even more red due to the further shift in wavelength.
Step-by-step explanation:
In this scenario, the apparent shift in the color of the light as you approach it is due to the Doppler effect. The Doppler effect is the change in frequency or wavelength of a wave as it is observed by an observer moving relative to the source of the wave. In this case, the light from the traffic light appears yellow to you because your motion towards the light has compressed the wavelength of the light, shifting it towards the blue end of the visible spectrum.
To calculate the speed at which you were approaching the light, we can use the equation for the Doppler effect:
v = (c * (f - f0)) / f0
where v is the velocity of the observer (you), c is the speed of light, f is the observed frequency of the light, and f0 is the rest frequency of the light.
By substituting the values of the observed and rest wavelengths, we can find the observed and rest frequencies:
f = c / λ
Using the obtained values of f and f0, we can calculate the velocity v at which you were approaching the light.
If the light had actually been yellow, which has a longer wavelength than red, it would have appeared even more red to you due to the further shift in wavelength towards the longer wavelength end of the visible spectrum.