# Electric Circuits

## Current, Resistance, Power

#### Ohm's Law and Temperature

RealVideo®
5:56 minutes (17:13 - 23:09)

Explanation that temperature can cause Ohm's Law to break down. Includes a demonstration of Ohm's Law holding for one resistor and not for another.

Instructor: Prof. Walter Lewin
Prior Knowledge: Ohm's Law (6:52 of VL9)

#### Demonstration: Breakdown of Ohm's Law

RealVideo®
4:01 minutes (23:09 - 27:10)

Ohm's Law failing to hold for a light bulb with a resistance that varies with temperature.

Instructor: Prof. Walter Lewin
Prior Knowledge: Ohm's Law (6:52 of VL9)

#### Demonstration: Increasing the Conductivity of Air

RealVideo®
4:15 minutes (32:38 - 36:53)

Using a candle to increase the conductivity of air near an electroscope.

Instructor: Prof. Walter Lewin
Prior Knowledge: Ohm's Law (6:52 of VL9)

#### Demonstration: Increasing the Conductivity of Water

RealVideo®
6:15 minutes (36:53 - 43:08)

Using salt to increase the conductivity of water and light a bulb.

Instructor: Prof. Walter Lewin
Prior Knowledge: Ohm's Law (6:52 of VL9)

RealVideo®
6:08 minutes (43:08 - 49:16)

Calculation of resistance between body and Earth through a pair of shoes, including a demonstration that this resistance is not high enough to keep charge from flowing.

Instructor: Prof. Walter Lewin
Prior Knowledge: Ohm's Law (6:52 of VL9)

#### Demonstration: Batteries in Series

RealVideo®
4:30 minutes (10:50 - 15:20)

Connecting two batteries in series to demonstrate that the electromotive force doubles.

Instructor: Prof. Walter Lewin
Prior Knowledge: Power Supplies (Beginning of VL10)

#### Power in a Battery

RealVideo®
4:33 minutes (23:57 - 28:30)

Finding the power supplied by a battery, with a demonstration of a 9V battery being shorted out.

Instructor: Prof. Walter Lewin
Prior Knowledge: Power (15:20 of VL10)

#### Demonstration: Shorting a Car Battery

RealVideo®
2:48 minutes (28:30 - 31:18)

Showing the large current and power supplied by a car battery when it is shorted out.

Instructor: Prof. Walter Lewin
Prior Knowledge: Power (15:20 of VL10)

#### Demonstration: Kelvin Water Dropper

RealVideo®
6:01 minutes (44:02 - 50:03)

A power supply generated from falling water. Not explained until a later lecture.

Instructor: Prof. Walter Lewin
Prior Knowledge: None