This is a direct link to the Physlet Blackbody Radiation animated tutorial, developed by Mario Belloni, Anne Cox, and Wolfgang Christian. Students can set the temperature from 300 to 30,000K, then click to view graphs of energy density v. wavelength. You can generate three types of curves: 1) Based on Rayleigh-Jeans formula (which stops working at high frequencies), 2) Based on Planck's Constant (the accurate curve), and 3) Side-by-side view of both the R-J and Planck curves. The tutorial nicely explains how Planck solved the Ultraviolet Catastrophe problem to build a formula that agreed with the experimental data. We especially like this Physlet because each formula is broken down into constituent parts and thoroughly explained.

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In this physlet, students can adjust temperature from 300-30000K and a graph will be generated of energy density per wavelength for the given temperature chosen. It's a good way to visualize the relationship maximum energy density and temperature that underlies λ_maxT = constant.

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Want to satisfy your craving for geometry geekery? This beautifully animated video is for you. In 15-minutes, the folks at the 3Blue1Brown YouTube channel illustrate why the formula for surface area of a sphere works and why it is exactly double the surface area of a cylinder with an equal radius minus its circle ends. The author uses a more traditional approach to the geometry in the first half of the video, using cutaways of hemispheres plus a stunning visualization where the sphere is divided into many tiny quadrilaterals projected onto an imaginary cylindrical surface. He then pivots to introducing his own visualization of "unfolding" four circles into triangles and illustrating how they fit neatly into the rectangle formed by a cylinder without its ends. To explain that the sphere's surface area is four times its "shadow", he offers up a proof accompanied by animations of a sphere cut into many rings parallel to the xy plane.

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Here are three very user-friendly animations to help students visualize solar insolation, the amount of incoming solar radiation received over a unit area of surface. It measures the solar energy incident on a specified location over a period of time. Students might especially appreciate the second and third animations which display light radiation in terms of the latitude and day of the year. Move the sliders to change the latitude and the array tilt. The geometry is fully explained at the end of the tutorial. Quite helpful for exploring different variables that affect surface temperature on a rotating planet with axial tilt (like Earth).

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This animation-based tutorial does a great job helping students visualize what blackbody radiation is, tips for "taking care" with the units in calculation, and exploring how the Stefan Boltzmann Constant is used to calculate total power density. Why we like it: It has a very responsive/intuitive user-controlled graph of spectral intensity vs. wavelength and it is appropriate for upper division courses. Easy to visualize the big picture.

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This video-based tutorial from Princeton's PPPL is appropriate for both lower and upper division. We especially like the 3-minute video explaining the fusion reaction. This resource relates well to Question 3B of the Lecture Tutorial in this DigiKit, which explores the hydrogen fusion sequence on stars like our Sun.

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