Modern Physics Lab
Reference constants and interactive Relativity & Quantum calculators.
| Constant Name | Symbol | Approx Value | Unit | Category |
|---|---|---|---|---|
| Speed of Light in Vacuum | c | 2.998 × 10⁸ | m/s | Universal |
| Planck Constant | h | 6.626 × 10⁻³⁴ | J·s | Quantum |
| Elementary Charge | e | 1.602 × 10⁻¹⁹ | C | Atomic |
| Electron Mass | m_e | 9.109 × 10⁻³¹ | kg | Atomic |
| Proton Mass | m_p | 1.673 × 10⁻²⁷ | kg | Atomic |
| Neutron Mass | m_n | 1.675 × 10⁻²⁷ | kg | Atomic |
| Avogadro Constant | N_A | 6.022 × 10²³ | mol⁻¹ | Chemistry |
| Boltzmann Constant | k_B | 1.381 × 10⁻²³ | J/K | Thermal |
| Gas Constant | R | 8.314 | J/(mol·K) | Thermal |
| Gravitational Constant | G | 6.674 × 10⁻¹¹ | N·m²/kg² | Universal |
| Rydberg Constant | R_∞ | 1.097 × 10⁷ | m⁻¹ | Quantum |
| Stefan-Boltzmann Const. | σ | 5.670 × 10⁻⁸ | W/(m²·K⁴) | Thermal |
| Permittivity (Free Space) | ε₀ | 8.854 × 10⁻¹² | F/m | EM |
| Permeability (Free Space) | μ₀ | 4π × 10⁻⁷ | T·m/A | EM |
The Code of the Universe.
Why is the speed of light exactly 299,792,458 m/s? We don't know *why*, but we know that if it were slightly different, atoms wouldn't form and stars wouldn't shine.
Matter is Frozen Energy
Einstein revealed that mass and energy are the same thing (Equivalence).
That's enough energy to power a small city for a day, locked inside a paperclip.
The Universe is Pixelated
Quantum Mechanics says energy is not continuous like a ramp, but discrete like a staircase.
The height of each step is determined by Planck's Constant ($h$).
Constants Table
Frequently Asked Questions
What is E=mc²?
It is Einstein's famous equation for Mass-Energy Equivalence. It states that mass and energy are interchangeable. Because 'c' (speed of light) is such a huge number ($3 \times 10^8$), typically a tiny amount of mass converts into a massive amount of energy.
What determines the energy of a photon?
The energy of a photon depends entirely on its frequency (color). High-frequency light (UV, X-Rays) has high energy, while low-frequency light (Radio, Infrared) has low energy. The formula is $E = hf$.
Why is the speed of light the limit?
As an object with mass accelerates, its effective mass increases. As you approach 'c', the mass approaches infinity, requiring infinite energy to accelerate further. Therefore, only massless particles (like photons) can travel at light speed.
What is the Planck Constant (h)?
The Planck Constant ($6.626 \times 10^{-34} \text{ J} \cdot \text{s}$) is the fundamental 'pixel size' of action in the universe. It scales quantum effects. If 'h' were zero, the world would be continuous and Newtonian. Because 'h' is non-zero, energy is 'quantized' into chunks.
What is an Electron-Volt (eV)?
An Electron-Volt is a tiny unit of energy used in atomic physics. It is the energy gained by an electron accelerating through 1 volt. $1 \text{ eV} = 1.602 \times 10^{-19} \text{ Joules}$.
What is Wave-Particle Duality?
Light behaves like a wave (interference patterns) AND a particle (photoelectric effect). Similarly, matter (electrons) behaves like a particle AND a wave. This is the core mystery of Quantum Mechanics.
Why are atomic masses not whole numbers?
Protons and Neutrons have slightly different masses. Also, when they bind into a nucleus, some mass is lost as 'Binding Energy' ($E=mc^2$). This is why Carbon-12 is exactly 12, but other atoms vary.
What is the Fine Structure Constant?
It is a dimensionless number ($approx 1/137$) that characterizes the strength of the electromagnetic interaction. It determines how strongly electrons bind to protons.
What is the Photoelectric Effect?
It is the emission of electrons when light hits a material. It proved that light comes in packets (photons). If the photon energy is too low (red light), no electrons are ejected, no matter how bright the light is.
Can we convert energy back into mass?
Yes! High-energy photons (Gamma rays) can spontaneously turn into a particle-antiparticle pair (e.g., an electron and a positron). This is called Pair Production.