Rainbow Formation
A rainbow is a natural phenomenon where the dispersion of light is most visible. As you know, We can see a rainbow after it rains because the water droplets bend and disperse the light. For example, if we spray water … more
Rainbow Colors
Color and Eye Recognition Visible light has various colors. Light has a different color depending on the wavelength (or frequency). So, how do people perceive color? Cone cells in the eye’s retina recognize color. There are three kinds of cone … more
Principle of Mirror
Why is the incident angle and the reflection angle the same? ‘Law of reflection’ has the word ‘law’ attached. ‘Law’ refers to a situation in which a natural phenomenon happens repeatedly and without exceptions. In other words, ‘law’ only tells … more
Is Sun Rays Parallel?
Parallel sunlight The radiant energy of the sun spreads in every direction. However, since the sun and the earth are far apart, we assume that they are usually almost parallel. Ancient Greece’s Eratosthenes measured Earth’s size quite accurately, assuming that … more
Parallax of Eyes
Parallax When an object is close to me, you can use a ruler to measure the distance. But, it isn’t easy to measure when the object is away from me. In this case, how can you measure the distance? Humans … more
Law of Reflection
The law of reflection Consider a light-ray incident on a plane mirror, the angle of reflection is equal to the incidence angle. This is the law of reflection. When looking at the end of the head and feet with a … more
Maximum Elongation of Inner Planets
Maximum Elongation of Inner Planets From the Earth’s perspective, the inner planets seem to stay near the sun. This is because it orbits the inside of the earth. So We cannot see the inner planets in the middle of the … more
Fourier Analysis
Fourier series A Fourier series is a way to represent a function as the sum of simple sine waves. A simple trigonometric function consists of a smooth surface. If you continue to add these trigonometric functions, you can get a … more
Formation Model of Columnar Joint
Formation of Columnar Joint A columnar joint appears as a polyhedral pillar, such as a tetragonal, pentagonal, or hexagonal shape. Its shape depends on the rate at which the lava solidifies. Columnar joints are often mistakenly known to be hexagonal … more
Differentiation
Differentiation The differentiation is to find the amount of change at a point on a graph f(x). This is like the process of finding the slope of the tangent line when you can draw a tangent at a point on … more
Stellar Parallax
Parallax When an object is close to me, you can use a ruler to measure the distance. But, it isn’t easy to measure when the object is away from me. In this case, how can you measure the distance? Humans … more