An introduction to the Cosmological Time Scale 2. Created by Sal Khan.
This 10-minute video lesson looks at the beginnings of life on Earth. Life and photosynthesis start to thrive in the Archean Eon. [Cosmology and Astronomy playlist: Lesson 39 of 85]
This 10-minute video lesson looks at the formation of the Earth which is a the byproduct of a local supernova. [Cosmology and Astronomy playlist: Lesson 38 of 85]
This 11-minute video lesson looks at Potassium-Argon (K-Ar) dating and it can be used to date very old volcanic rock and the things that might be buried in between. [Cosmology and Astronomy playlist: Lesson 79 of 85]
Sal explains the fundamental force that causes charged particles to attract or repel each other.
Covalent bonds involve the sharing of electron pairs between atoms. Electron pairs shared between atoms of equal or very similar electronegativity constitute a nonpolar covalent bond (e.g., Hƒ??H or Cƒ??H), while electrons shared between atoms of unequal electronegativity constitute a polar covalent bond (e.g., Hƒ??O). Created by Sal Khan.
Creating motor mounts. Created by Karl Wendt.
How do we draw a surface of water using only particles? In this video we'll introduce a powerful analogy using heat to help us out.
How to use SQL to create a table and insert data into a database.
An overview of Creating elements from scratch
Learn how to use jQuery to create elements from scratch and then insert them at different places in your webpage.
Introduction to the cross product. Created by Sal Khan.
A little more intuition on the cross product. Created by Sal Khan.
The positive sign for current corresponds to the direction a positive charge would move. In metal wires, current is carried by negatively charged electrons, so the positive current arrow points in the opposite direction the electrons move. This has been the sign convention for 270 years, ever since Ben Franklin named electric charges with + and - signs. This convention came about 150 years before the discovery of the electron. Created by Willy McAllister.
Find the current due to closing a switch using equivalent resistance and Ohm's law.
How to calculate the current through a resistor in parallel using equivalent resistance and Ohm's law.
Google Security Princess Parisa Tabriz and Jenny Martin from Symantec introduce the most common types of cybercrime, including viruses, malware, DDOS attacks and phishing scams.
Learn about DNA (deoxyribonucleic acid). Overview of DNA bases, complementary base pairing, and the structure of the double helix.
Introduction to DNA sequencing.
Overview of DNA and chromatin regulation.