#AP Physics 2: Quantum Physics - Your Last-Minute Guide 🚀

Hey there, future physics pro! Let's get you prepped and confident for your AP Physics 2 exam. This guide is designed to be your go-to resource, especially the night before the big day. We'll break down the key concepts, highlight must-know info, and tackle some practice problems together. Let's do this! 💪

#7.5 Wave-Particle Duality and Quantum Phenomena

#Wave-Particle Duality: The Basics 🤯

Remember how light can act like both a wave and a particle? Well, this duality isn't just for light; it applies to all fundamental particles! This idea is called wave-particle duality.

• Particles as Waves: On a tiny scale, particles (like electrons) can show wave properties. Think of the double-slit experiment where particles diffract, just like waves. 🌊
• Waves as Particles: Waves (like photons) can also show particle properties. Photons have momentum and energy related to their frequency and wavelength. 💡

#Compton Effect: Proof of Photon Momentum

In the 1920s, Arthur Compton showed that when an X-ray photon hits an electron, momentum is conserved. This is known as the Compton effect. The scattered photon has a lower frequency than the original photon.

Caption: The Compton effect demonstrates the particle-like behavior of photons, showing that they have momentum.

#De Broglie Wavelength: Particles as Waves

Louis de Broglie proposed that if a photon's momentum is $p = \frac{h}{\lambda}$, then the wavelength is $\lambda = \frac{h}{p}$. He suggested that particles could also have a wavelength. For a particle with mass m and velocity v, the de Broglie wavelength is:

$$\lambda = \frac{h}{mv}$$

• Key Point: For a noticeable wavelength, the mass has to be extremely small (like atomic scale). This is why we see wave-like behavior more with electrons than with everyday objects. ⚛️