Doppler Effect

The phenomenon by which an object’s emitted light frequency appears to change as it is moving. Objects moving towards an observer will have blueshifted frequencies, meaning they will appear closer to the blue end of the visible light spectrum (think closer to UV light). Meanwhile, the exact opposite happens for objects moving away from an observer, as they will be redshifted (think closer to infrared light). The equation for the observed wavelength is as follows:

$\frac{\nu}{v_{wr}} = \frac{1}{\lambda}$

Where:

${\nu}: observed \, frequency$

$v_{wr}: speed \: relative \, to \: observer$

Also the observed frequency is given by the following equation:

${\nu} = {\nu_0}\frac{c \pm v_r}{c \pm v_s}$

Where:

${\nu_0}: emitted \, frequency$

$v_r: speed \: of \, receiver$

$v_s: speed \: of \, source$

$c: speed \: of \, light$

The speed of the receiver is added to the speed of light if the receiver is moving towards the source and vice versa. Meanwhile, the opposite is true for the speed of the source compared to the receiver.