# Can you test a light bulb with a multimeter?

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## How do you check the continuity of a light bulb?

Touch one lead to the small metal knob on the bottom of the bulb and the other lead to the bulb threads. If the bulb doesn’t have threads, put the second lead on one of the two knobs that protrude from the side of the base. The bulb is good if the meter reads zero of the tester bulb lights up.

## How many ohms should a light bulb have?

The typical cold resistance of a 100 W incandescent lamp is about 9.5 ohms. If that resistance stayed the same with 120 V applied, Ohm’s Law tells us that the bulb would draw about 12.5 amps and dissipate about 1,500 watts.

## Can you Ohm a light bulb?

Check the bulb by determining the resistance of the filament. The filament is the wire inside of the bulb. The resistance can be checked by a multimeter. By setting the multimeter selector switch to ohms it will read ohms for you.

## Does a light bulb follow Ohm’s law?

Neither the incandescent bulb nor the LED will follow Ohm’s Law, neither produces a linear graph. Teachers are strongly encouraged to set up and try this activity ahead of time. Equipment from school to school varies. If it’s nonexistent, Radio Shack is a good source of equipment.

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## Does the resistance of a light bulb change?

The filament in an incandescent bulb does not have a constant resistance. … An increase in current means the bulb gets hot—hot enough to glow. As the temperature increases, however, the resistance also increases.

## How do I test a light socket with a multimeter?

Press the red probe for the multimeter against the electrical connections inside the light bulb socket. If the vehicle is a 12-volt system, the multimeter should register 12 volts. Vintage cars often ran on 6-volt systems and commercial trucks routinely work on 24-volt systems.