Photons, Electrons, Energy & Planck's Constant

Energy is

continuous, it does not stop

Electromagnetic force

The electromagnetic force is a fundamental, invisible force that causes electrically charged particles to either attract or repel each other

Photon

Think of a photon as a tiny, invisible "packet" of energy. It is the basic building block of light. Even though we usually think of light as a smooth wave (like a wave in the ocean), it is actually made up of these tiny, individual particles. It travels at the speed of light, carries energy, and acts as the carrier of the electromagnetic force. They behave like both a particle and a wave. A photon has no mass (it weighs nothing) and no electric charge. Its only "job" is to carry energy from one place to another at the speed of light. A photon's energy is determined by how fast it vibrates. High-frequency photons (like X-rays) have a lot of "punch." Low-frequency photons (like Radio waves) have very little "punch."

• Light is made of Photons.

• Photons carry energy based on their Frequency (Hz).

• Electrons absorb that energy to move or create Electricity.

Frequency (Hz) or (v)

Represented by Hz or V. It is a measure of how often an event, action, or wave repeats within a specific period

Wavelength (λ)

Represented by (λ) lambda. Wavelength is the distance from one point on a wave to the same point on the next wave. The physical distance between two consecutive, identical points on a wave, such as from one peak (crest) to the next. It represents the length of one complete wave cycle, typically measured in meters, centimeters, or nanometers. Shorter distances indicate higher frequencies; longer distances indicate lower frequencies

Wavelength and frequency are

inversely proportional. (one goes up, the other goes down).

Speed of light ( c )

c = λ (wavelength) x v (frequency)

c =

3.0 × 10⁸ m/s

1 Hz = S^-1

When you see , just read it in your head as "per second." The number 1 just represents "one cycle" or "one event." If a heart beats 2 times per second, it is 2 Hz or 2s^-1. So, one [event] per second.

Photons and Electrons

Think of the relationship between a photon and an electron like a delivery driver and a customer. The photon is the delivery driver carrying a "package" of energy. The electron is the customer waiting inside the atom to receive it. When a photon hits an atom, it doesn't just bounce off like a ball. If the photon has the right amount of energy, the electron absorbs it. The photon disappears, and its energy is transferred entirely to the electron. Electrons live in specific "floors" (energy levels) around an atom.

• When the electron takes the energy from the photon, it gets a "boost."

• It jumps from a lower floor to a higher floor.

The Connection: The higher the frequency of the photon (more Hz or), the higher the "floor" the electron can jump to.

What determines the frequency of a photon

How much energy was used to create it in the first place. This is the most common way. Electrons live on different "floors" (energy levels) in an atom.

• The Drop: When an electron falls from a high floor to a lower floor, it has to get rid of that extra energy.

• The Result: It spits out a photon.

• The Rule: The "bigger" the drop (the more energy lost), the higher the frequency of that photon.

  • A small drop might create a Red photon (low frequency, fewer Hz).

  • A huge drop might create a Blue or Violet photon (high frequency, more Hz).

Everything that is warm glows, even if we can't see it. This is called Thermal Radiation.

• Hotter objects have atoms that are shaking and crashing into each other very violently.

• These violent crashes create photons with high frequencies.

Ultimately, the frequency depends on the source:

• A Radio Tower pushes electrons back and forth slowly to create low-frequency radio photons.

• An X-ray machine crashes high-speed electrons into metal to create high-frequency X-ray photons.

The photon-electric effect

is a phenomenon where light shining on a material (usually a metal) causes it to shoot out electrons. A "particle" of light hits the metal surface, an electron inside the metal absorbs the photon’s energy, if the photon has enough energy, it "kicks" the electron right out of the metal. Color (Frequency) Matters: If the light is below a certain frequency (like red light), no electrons come out, no matter how bright the light is. Brightness (Intensity) Doesn't Affect Speed: A brighter light makes more electrons pop out, but it doesn't make them move any faster.

• Solar Panels: They turn sunlight directly into an electric current using this effect.

• Automatic Doors: When you walk through a "magic" door at a grocery store, you are often breaking a beam of light that was using the photoelectric effect to create a signal.

• Digital Cameras: The sensor in your phone captures light by turning incoming photons into electrons to form an image.

If the photon is powerful enough (high energy), it doesn't just move the electron to a higher floor—it kicks it completely out of the building.

• This is exactly what happens in a solar panel.

• Photons from the sun hit electrons in the silicon, knocking them loose.

• Those loose electrons moving around create the electricity that powers your house.

This connection works both ways! If an electron drops from a high floor back down to a lower one, it has to get rid of that extra energy. It does this by spitting out a photon.

• This is how an LED light bulb works. We push electrons into higher levels with electricity, and when they fall back down, they release photons that we see as light.

Summary:

• Photons = Energy carriers (Light).

• Electrons = Energy absorbers/emitters (Matter).

Electrons make photons and vice-versa

Electrons: When an electron falls from a high floor to a lower floor, it has to get rid of that extra energy. It spits out a photon. The "bigger" the drop (the more energy lost), the higher the frequency of that photon.

Photons: Imagine a high-energy photon zooming past the center of an atom (the nucleus). The intense gravity/energy there causes the photon to vanish. The Photon is a runner with a lot of energy.

1. The Electron is sitting on a bench, tired.

2. The Photon runs up and "tags" the electron.

3. The Result: The Photon stops moving (it disappears), and the Electron suddenly has all that energy and starts running.

The photon is absorbed. It’s like a raindrop hitting a sponge. The raindrop (photon) "disappears" because it is soaked up, but the sponge (electron) is now "wet" (full of energy).

Phi (Φ)

(represents work function). It means the "Escape Energy." It is the specific amount of energy an electron needs to "break the glue" holding it to a metal. It’s the energy the metal demands from a photon: its the energy a metal needs from a photon to release an electron. EX: Φ Fe is 7.21 × 10^-19J 1. The Glue

The Phi (Φ) is the strength of that glue. It’s the "cost" of ripping the sponge off the table.

1. The Raindrop (Photon)

The photon is a raindrop falling toward the sponge. It carries a specific amount of energy (E_photon) based on its frequency (Hz).

2. The Connection

When the raindrop hits the sponge, the sponge absorbs it. Now, one of two things happens:

• Scenario A (Not enough Hz): The raindrop is too small. The sponge gets a little wet, but it doesn't have enough energy to break the glue. It stays stuck to the table. No electricity.

• Scenario B (Enough Hz): The raindrop is big and powerful. The sponge absorbs it and suddenly has enough "oomph" to snap the glue (Φ) The sponge rips off the table and flies into the air! Electricity!

3.The "Leftover" Energy

If the raindrop had 10 units of energy and the glue (Φ) only cost 7 units to break:

1. 7 units are used up immediately just to break the glue. (This energy is "spent").

2. 3 units are left over. The sponge uses this leftover energy to fly away fast.

The leftover energy is used for speed (Kinetic Energy)

E photon

the energy of a photon. The size of the punch that the photon carries. E photon is the amount of energy inside one single photon.

Phi (Φ) and E_photon

Phi (Φ) is the amount of energy needed for a photon to (make a electricity) kick an electron out, and E_photon is the amount of energy that the photon contains. SO:

E_photon > Φ = electrons are kicked out with kinetic energy

E_photon = Φ: Electron is kicked out with no kinetic energy (the electron just barely makes it out)

E_photon < Φ = no electrons are kicked out

Planck’s Constant (h)

Planck’s constant (h) = 6.626 × 10^-34 J x Seconds. It is the "conversion factor" of the universe. It is the number that turns frequency (how fast something wiggles) into energy (how much "punch" it has).

E_photon = ? (J)

E_photon (energy of a photon) = h (Planck’s constant) x v (frequency)