An ohmmeter tests the electrical resistance and current between two leads. Ohmmeters come in a variety of shapes, sizes and expenses and can be used to test resistance on a wide range of electrical components and determine whether they are defective.
When an ohmmeter points to the infinity symbol, it means that there is no continuity between the two test leads and that an open circuit is present.
The way an ohmmeter is set up may be confusing. The infinity sign is on the far left of the meter, while the zero is on the far right. This is because analog ohmmeters read from right to left. When using an ohmmeter, it is important to note that a short circuit will record as a very low reading, not a reading of infinity.
Make sure the switch for the appliance or equipment you are testing is turned on even though it is not plugged into an electrical outlet. If the switch is turned off, the ohmmeter may record an infinite reading--that is, an open circuit.