KORAKU vs Pocket Experiments Science Lab

KORAKU is an interactive educational app for exploring optical phenomena through simulation. The fourth in the series following SUUGAKU (Math), BUTURAKU (Physics), and HARAKU (Waves). This time the theme is "Light." From geometrical optics to quantum-scale phenomena, experience ten simulations of how light behaves. [10 Simulations] - Lens (Thin Lens) Observe ray paths and image formation through convex and concave lenses in real time. Adjust focal length, object distance, and object height to experience the thin lens equation (1/f = 1/a + 1/b). - Spherical Mirror Toggle between concave and convex mirrors to visualize image formation. Move the object and change the radius of curvature to see real vs. virtual and upright vs. inverted images. - Prism Dispersion Simulate white light passing through a prism and separating into a rainbow spectrum, based on Snell's law and the Cauchy dispersion formula. - Rainbow Trace light entering a raindrop, refracting, reflecting internally, and exiting. Wavelength-dependent deviation reproduces the primary and secondary rainbows around the antisolar point. - Diffraction Grating Visualize multi-slit interference patterns. Change slit spacing and wavelength to understand the diffraction condition d sin(θ) = mλ. - Optical Fiber Simulate light propagation by total internal reflection. Adjust the launch angle and refractive indices to learn the relationship between critical angle and numerical aperture (NA). - Polarization Change the angles of the polarizer and analyzer to observe transmitted light intensity following Malus's law (I = I₀cos²θ). - Thin Film Interference Reproduce the rainbow colors of soap bubbles and oil films. Adjust film thickness, refractive index, and incident angle to observe interference based on optical path difference. - Color Mixing Compare additive color mixing (RGB light) and subtractive color mixing (CMY pigments). Three channel sliders show the resulting RGB values in real time. - Photoelectric Effect Animate electrons being ejected from a metal by photons. Three sliders for frequency, intensity, and work function let you feel the relationships E = hf, Kₘₐₓ = hf − W, and threshold f₀ = W/h. [Features] - Adjust parameters in real time across all simulations - Physics formulas and values displayed in real time - Dark mode / Light mode support - Japanese / English support - iPhone / iPad support [Pricing & In-App Purchases] - The app itself is completely free - No in-app purchases of any kind - No subscriptions - No paid additional content - A small banner ad (Google AdMob) is shown at the bottom of the screen - Ad personalization may use the iOS App Tracking Transparency permission (optional) [Recommended For] - Students studying optics in physics class - Anyone who wants to intuitively understand the properties of light - Teachers looking for teaching materials - Anyone interested in optics

Twenty-six rooms. Not a workbook — a bench in each one. You set the parts out yourself, turn the knobs, and measure with the instruments. • Hang as many weights as you like anywhere along a balance beam, and even it up • Drag molecules onto the bench and see what they form • Set a magma's silica and the depth where it freezes, erupt it, then look at the rock through a hand lens and measure the grains • Stretch two strings, detune one, and listen to the beats • Drop three seismometers on a map; three circles meet at one point, and that point is the epicenter Every number is measured off the picture. Nothing here works a value out of a formula and then "checks" it against the same formula. The grains under the lens are really drawn, and their size is really measured. Turn a knob and the picture changes; when the picture changes, the numbers change with it. Every room has three steps: 1. Move it — turn one knob and watch what changes 2. Count it — line the measurement up against the formula and look at the gap 3. Check it — one question, and the reason either way Every room also has a question box. Clear it and the room moves up a tier: none → bronze → silver → gold. There are 78 questions in all. But the questions are not the main act. Playing with the bench is; a question is the detour you take when you think “wait — could I actually build that?” The topics are middle school and high school science: forces and motion, springs and buoyancy, pendulums, circuits, electromagnets, ray optics, lenses, sound, changes of state, solubility, titration, electrolysis, chemical reactions, preparing and collecting gases, the microscope, cell division, photosynthesis, flower structure, heredity, strata, rocks and volcanoes, earthquakes, and the sky. Three neighbors of science come along too: probability, logic gates and regular expressions. ADS AND THE ONE-TIME PURCHASE The app is free and shows ads: a banner along the bottom of the screen, and a full-screen ad when you open the app. All 26 rooms and all 78 questions are open from the first launch. There is exactly one in-app purchase and all it does is turn the ads off — it unlocks nothing and adds nothing. It is a single one-time purchase with no subscription (¥5,000 in Japan; the price for your country is shown in the app). Not based on, or affiliated with, any particular textbook.