Prepared by the world's best academic note publisher for an IBDP Physics class

We'll start by diving into the Doppler Effect, but for light waves instead of sound waves. You might remember the Doppler Effect from those times you've heard an ambulance's siren change pitch as it zoomed past you. Well, light waves have their own version of the Doppler Effect, and it's just as exciting! 🚑🔊

First, let's refresh what we know about electromagnetic radiation. It includes light and other waves you might have heard of, like X-rays or radio waves. Here are the key things you need to know

• Electromagnetic radiation doesn't need a medium to travel. That means it can travel through the vacuum of space. Pretty cool, right? 🚀
• The speed of light is always the same. No matter who's looking at it or how fast they're moving, light always travels at the same speed – about 300,000 kilometers per second in a vacuum.
• Source speed and observer speed don't really apply to light. In special relativity, the motion of a source and an observer can't be distinguished. So instead, we talk about the relative velocity between them. 🌀

When we deal with light and the Doppler Effect, the math is a bit different from sound. Here's how we calculate the change in frequency (Δf) when the relative speed (v) between a source and an observer is much less than the speed of light (c)

\(\frac {Δf}{f}​≈ \frac vc\)

And, just like with sound waves, we can apply this equation to the fractional change in wavelength (Δλ/λ).

Please note that these equations are only valid when the relative speed between source and observer is much less than the speed of light. 🚀