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OHMS LAW

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To understand all electronics you must first understand Ohm's Law. The three main elements of Ohm's Law are Voltage which is referred to as V or sometimes E, Current which is referred to as I, and Resistance which is referred to as R.

VOLTAGE

Voltage is an electric potential difference between two points on a conducting wire. Voltage is measured in volts. Voltage comes from various sources. Two examples of these sources are batteries and electrical outlets.

CURRENT

Current is measured in amps. Current is charged particles which flow from the voltage source through conductive material to a ground.

RESISTANCE

Resistance is the opposition that a material body offers to the passage of an electric current. Resistance is measured in ohms. Examples of items with resistance are light bulbs, hair dryers, toasters.

OHM'S LAW

V = I x R

Where:

V = Voltage

I = Current

R = Resistance

Example Problem:

A nine volt battery supplies power to a cordless curling iron with a resistance of 18 ohms. How much current is flowing through the curling iron?

Sketch:

Solution:

1.) Since V(Voltage) and R(Resistance) are known, solve for I(Current) by dividing both sides of the equation by R.

2.) The R's on the right hand side of the equation cancel.

3.) I is then left in terms of V and R.

4.) Substitute in the values for V(Voltage) and R(Resistance).

5.) Solve for I(Current).

Problem #1

A 110 volt wall outlet supplies power to a strobe light with a resistance of 2200 ohms. How much current is flowing through the strobe light?

Sketch:

Choose your answer below

0.5 amps
2.0 amps
0.05 amps
1.0 amps

Problem #2

A CD player with a resistance of 40 ohms has a current of 0.1 amps flowing through it. Sketch the circuit diagram and calculate how many volts supply the CD player?

Choose your answer below

0.0025 volts
4.0 volts
10.0 volts
400.0 volts

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