What happens when there's way more than two holes? Created by David SantoPietro.
The index of refraction in a material isn't always the same for every wavelength. This is how prisms split white light into so many colors. Created by David SantoPietro.
Understanding the differences between the dot and cross products. Created by Sal Khan.
In this video David explains why physicists came up with the idea of the electric field, how it's useful, and explains how the electric field is defined. Created by David SantoPietro.
The direction of an electrical field at a point is the same as the direction of the electrical force acting on a positive test charge at that point. For example if you place a positive test charge in an electric field and the charge moves to the right you know the direction of the electric field in that region points to the right. Created by David SantoPietro.
Sal shows that there will be a net torque on a loop of current in a wire. Sal shows that this net torque will cause the loop to rotate. Created by Sal Khan.
Sal shows that a commutator can be used in order to keep the loop of wire rotating in the magnetic field. Created by Sal Khan.
Sal finishes the explanation of how a commutator will allow a loop of wire to continue spinning in a magnetic field, thereby allowing it to work as an electric motor. Created by Sal Khan.
David explains electric potential (voltage). Created by David SantoPietro.
In this video David explains how to find the electric potential energy for a system of charges and solves an example problem to find the speed of moving charges. To see the calculus derivation of the formula watch this video. Created by David SantoPietro.
In this video David shows how to find the total electric potential at a point in space due to multiple charges. Created by David SantoPietro.
Introduction to electromagnetic waves and the electromagnetic spectrum.
An emf induced by motion relative to a magnetic field is called a motional emf. This is represented by the equation emf = LvB, where L is length of the object moving at speed v relative to the strength of the magnetic field B.
Using Balmer-Rydberg equation to solve for photon energy for n=3 to 2 transition. Solving for wavelength of a line in UV region of hydrogen emission spectrum. Created by Jay.
This video explains the potential of a capacitor and how they function in a circuit. By David Santo Pietro.
A hairy resistance problem. Created by Sal Khan.
Using exponential decay equation to solve for relationship between k and half-life. Using semi-log plot to get graph of a straight line with slope of -k. Created by Jay.
Showing that N(t)=Ne^(-kt) describes the amount of a radioactive substance we have at time T. For students with background in Calculus. Not necessary for intro chemistry class. Created by Sal Khan.
Introduction to Exponential Decay. Using the exponential decay formula to calculate k, calculating the mass of carbon-14 remaining after a given time, and calculating the time it takes to have a specific mass remaining . Created by Sal Khan.
How a current can be induced in a loop of wire by a change in magnetic flux.