**Wolfram Alpha website **is the Google of math and physics. If you want to do calculations on Wien's Law, you type "wien's law" and you will get a calculator for Wien's Law with all sorts of other information. The purpose of this activity is to practice some basic calculations of physical properties of sunlight.

### Short Problems:

- Use
**Wolfram Alpha**to calculate the**most probable wavelengths**emitted by the surface of the Earth (T=300 K) and the Sun (T=5778 K) using one or more of the laws discussed on the previous page of this lesson. What is the meaning of the "most probable wavelength"? - Use
**Wolfram Alpha**to calculate the energy flux (**radiant exitance**) emitted by those Earth's and Sun's surfaces using Stefan-Boltzmann Law. - Apply the Inverse Square Law (see formula on page 3.2 of this lesson) to determine the "
**extraterrestrial solar flux**" at the Earth using the Sun's radiant exitance found in Question 2. - Discuss the meaning of "
**extraterrestrial solar flux**" and how it is further transformed within the Earth's atmosphere.

This video below (6 min) presents a short demo on how to use the Wolfram Alpha site. The Stefan-Boltzmann Law is used as an example here, so it provides you with a tip for solving the second problem.

*© Penn State University is licensed under*

*CC BY-NC-SA 4.0*

### Submitting Your Work

Prepare a written report with your solutions and upload it to Canvas (Lesson 3 Learning Activity Dropbox) in PDF or docx format. You can use Wolfram Alpha screen shots to present your results for the first two problems (insert the screenshots into your report - don't submit them as separate files). Make sure to present the equations you are using and provide comments to the steps in your solutions.

### Grading Criteria

View the Rubric in Canvas by which this assignment will be graded.

### Deadline

See the Calendar tab in Canvas for specific due dates.