Physics Explained
Motion, forces, energy, heat, waves, light, electricity, magnetism and optics.
Motion, speed and acceleration
Motion is described relative to a reference point, while speed and acceleration describe how position and velocity change over time.
GuideForces and Newton's laws in everyday motion
Forces change motion, and Newton's laws provide a compact framework for understanding pushes, pulls and acceleration.
GuideGravity from falling objects to orbits
Gravity attracts masses and shapes motion from a dropped object to the orbit of the Moon.
GuideHow friction makes motion possible—and resists it
Friction opposes relative sliding, yet walking, driving and gripping objects depend on it.
GuidePressure in air and liquids
Pressure is force distributed over area, and it helps explain atmospheric effects, hydraulics and why fluids push in all directions.
GuideEnergy: forms, storage and transfer
Energy is a conserved quantity that can be stored and transferred in many ways.
GuideConduction, convection and radiation
Heat transfer occurs through particle interactions, fluid motion and electromagnetic radiation.
GuideHow insulation slows heat transfer
Insulation works by reducing the rate at which thermal energy moves through a material or assembly.
GuideHow sound waves work
Sound is a mechanical disturbance that travels through matter as variations in pressure and particle motion.
GuideLight and the electromagnetic spectrum
Visible light is only a narrow portion of the electromagnetic spectrum, which also includes radio waves, infrared, ultraviolet, X-rays and gamma rays.
GuideReflection and refraction
Light can bounce from surfaces, change direction when entering a new material and split into colours because wavelength matters.
GuideWhy the daytime sky looks blue
The sky looks blue mainly because molecules in the atmosphere scatter shorter visible wavelengths more strongly than longer ones.
GuideHow rainbows form
Rainbows appear when sunlight is refracted, reflected and dispersed inside many water droplets.
GuideColour: light, pigments and perception
Colour depends on the spectrum reaching the eye, how materials absorb or reflect wavelengths, and how the visual system interprets the signal.
GuideLenses, magnification and cameras
Curved lenses redirect light to form images, allowing eyes, cameras, microscopes and telescopes to focus or magnify details.
GuideElectricity and basic circuits
Electric circuits provide paths for charge to move and transfer energy through components.
GuideMagnetism and electromagnets
Magnetic fields arise from moving electric charges and magnetic properties of matter.
GuideHow batteries store and deliver energy
A battery uses chemical reactions to create an electrical potential difference between its terminals.