Dawn of modern Physics

Question 1

📷 What is the Photoelectric Effect?

Answer 1

When light falls on a metal surface, it can cause electrons to be ejected from the surface. This is called the photoelectric effect.

Question 2

💡 What Did Einstein Say in photoelectric effect?

Answer 2

Einstein had a new idea in 1905:
“Light is not just a wave. It’s made of tiny energy packets called photons.”
Each photon has energy:
Energyof1photon = hf
h = planks constant, f = frequency

Question 3

🔐 What is the Work Function?

Answer 3

If the photon’s energy is less than this strength:
1. Electrons can’t escape.
If the energy is more:
2. Electrons come out and move fast.

Question 4

🌟 What is “Radiation”?

Answer 4

The emission (release) of energy from a body — in the form of waves or particles.

Question 5

🌟 What is Quantum Theory?

Answer 5

“Hot objects do not emit energy continuously. They emit energy in small packets called quanta.”

Question 6

📸 What is Compton’s Effect?

Answer 6

The Compton Effect is the scattering (bouncing) of X-rays or gamma rays when they hit a particle like an electron.
👉 It shows that light behaves like particles (photons), not just waves.

Question 6

Explain the Experiment, What Compton Did?

Answer 6

1. Compton directed X-rays at a block of carbon (which has loose electrons).
   When X-rays hit the electrons, two things happened:
   1.An electron came out.
   2.A new X-ray bounced off in a different direction.
   This new X-ray had:
   -Less energy
   -Longer wavelength than the original one.
   🔁 This bouncing and energy loss is called the Compton Effect.

Question 7

🌟 What is the Uncertainty Principle?

Answer 7

He said:
“It is impossible to know the exact position and exact speed (momentum) of a tiny particle like an electron at the same time.”

Question 8

🔬 What is an Electron Microscope?

Answer 8

An electron microscope is a very powerful microscope that uses electrons instead of light to see very tiny details of objects — even atoms!

Question 9

What are SE AND BSE in EM?

Answer 9

SE are low-energy electrons that are knocked off from the atoms very close to the surface of the sample.
BSE are original electrons from the beam that are bounced back after hitting heavy atoms.

Question 10

🌊🔹 What is Wave-Particle Duality?

Answer 10

Wave-particle duality is a concept in quantum physics that means:
Tiny particles like light and electrons behave like both waves and particles.