There space three basic relationships worrying resistance, current, and voltage for all series circuits. That is necessary that you discover the three fundamental laws for collection circuits.

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Whenever separation, personal, instance resistances are associated in series, they have actually the same impact as one big combined resistance. Since there is only one route for current flow in a collection circuit, and since each of the resistors is in line to act together an opposition come this current flow, the in its entirety resistance is the combined opposition of all the in-line resistors.

The full resistance that a collection circuit is same to the amount of every the separation, personal, instance resistances in the circuit.

Rt = R1 + R2 + R3…

Using this formula, you discover that the total resistance of the circuit is:

RT = 15 Ω + 5 Ω + 20 Ω = 40 Ω

Figure 16. Series circuit








Since over there is only one course for electron circulation in a collection circuit, the present is the same magnitude at any point in the circuit.

The total current in a collection circuit is the same as the current through any type of resistance that the circuit.

IT = I1 = I2 = I3…

Given 120 V as the full voltage, and having established the complete resistance that the circuit together 40 Ω, you can now apply Ohms legislation to identify the total current in this circuit:

IT = 120 V/ 40 Ω = 3 A

This total circuit present would remain the same through every the individual circuit resistors.


Before any current will flow through a resistance, a potential difference, or voltage, should be available. As soon as resistors are associated in series, they have to “share” the complete voltage the the source.

The total voltage in a series circuit is equal to the amount of every the individual voltage autumn in the circuit.

As existing passes v each resistor in a series circuit, it develops a distinction in potential across each separation, personal, instance resistance. This is generally called voltage drop, and also its magnitude is in straight proportion come the worth of resistance. The better the value of resistance, the greater the voltage drop throughout that resistor.

ET = E1 + E2 + E3…

Using Ohms regulation you can determine the voltage throughout each resistor.

3 A × 15 Ω = 45 V

3 A × 5 Ω = 15 V

3 A × 20 Ω = 60 V

The total resource voltage is equal to the amount of the individual voltage drops:

45 V + 15 V + 60 V = 120 V

An open up in a series Circuit

If an open is introduced, current through the circuit is interrupted. If there is no current flow, the voltage drop across each that the resistive facets is zero. However, the potential difference of the source appears across the open. If a voltmeter is connected throughout the open, the reading is the very same as if that were associated directly across the terminals that the it is provided source.

Figure 17. Open circuit

Effects of line Drop and also Line Loss

Copper and aluminum are supplied as conductors due to the fact that they offer little opposition come the circulation of current. Return the resistance is often neglected in basic circuit analysis, it might be vital to think about the resistance of currently in valuable applications.

Line Drop

Figure 18. Volt drops

As the 10 A existing flows v each line resistance that 0.15Ω, a small voltage autumn appears across each line. This voltage drop across the heat conductors is generally referred to together a line drop.

Since there room two lines, the total drop is 2 × 1.5 V = 3 V. The net voltage throughout the pack (117 V) is less than the resource voltage.

In some situations, it might be crucial to used bigger conductors, which have actually lower resistance, so that the line drop walk not alleviate the fill voltage as well significantly.

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Line Loss

Another term connected with conductors is line loss. This is a power loss expressed in watts and also is concerned heat energy dissipation as present flows v the resistance the the line conductors. Heat loss is calculate by using among the strength equations.