Lab 2     Circuits

In this lab Ohm's law is verified and current flow in series and parallel resistive circuits is studied.

Equipment

Resistors


Figure 1   Resistors are labeled using colored bands
Resistors are labeled using colored bands. The first two bands are digits. The third band is the number of zeros. The fourth band gives the tolerance. For tolerance; no band represents 20%, silver represents 10%, gold represents 5%, and red represents 2%.

For example, consider the resistor shown in Figure 1. The color bands are brown, black, red, silver (1 0 2 10%). This is a 1000 Ohm resistor with 10% tolerance.

Color
Number
Black
0
Brown
1
Red
2
Orange
3
Yellow
4
Green
5
Blue
6
Violet
7
Gray
8
White
9

Table 1   Resistor color codes

Ohm's Law

Ohm's law states that the voltage across a resistor is proportional to the current flowing through the resistor.

Ohm's law does not hold in all situations. Resistors are designed using linear materials, so that resistors follow Ohm's law. Other useful devices such as diodes and transistors are nonlinear. They do not obey Ohm's law.