Ohm’s law circuit diagram [How to Read Symbols]

The simple Ohm’s Law Circuit Diagram comprises a resistance connected in series with a DC voltage source.


Two parallel lines having one with comparatively larger length represents the DC Source and a Zig-Zag symbol represents the resistor. Whereas the simple lines are used to represent the wires.

The above diagram is correct for the general case, practically we need to add an ammeter and a voltmeter for measurement purposes. Now our diagram with instruments will look like:


Let’s understand the components of our circuit diagram.

Battery: It is the dc voltage source which provides power to the internal circuit. As we studied the Ohm’s statement: V = IR. Actually, V is the battery or voltage source which powers the entire circuit.

Ammeter: It reads the current that flows through the entire circuit. Remember that an ammeter always connects in series to the circuit.

Voltmeter: It reads the voltage across the resistor. Remember that a voltmeter always joins in parallel to the component.

Now let’s start learning the basic mathematics of law using 5 Different Examples.

Example 1: A 10V battery connects in series with a 20k ohm Resistance. Find the current flowing through the circuit.

Solution: Using V1 = I1 R1.

I1 = V1/R1 = 0.5 mA

Example 2: A 15V source connects with an unknown resistor. The value of current is measured as 5 mA. Find the value of R.

Solution: R2=  V2/ I= 15V / 5mA = 3kΩ

Example 3: A 50k Resistor joins with a 25VDC Variable Supply. Find the value of unknown current that is flowing through this circuit.

Solution: I3  = V3 / R3 = 25V / 50k = 0.5mA

Example 4: The power dissipation through a 29k Resistance is 15watt. Find the value of current and input voltages supplied by the source.

Solution: Here the formulas: I = SQRT(P/R) and V = SQRT(P*R) will be used. You can learn about all these formulas from Ohmic Wheel.

Example 5: R5 = 10Ω and P5 = 20watt

Solution: V5 = 14.14 and I5 = 1.414