Series and Parallel Circuits

electric circuit

An electric circuit is a closed path through which electric charges can flow.

three main parts of electric circuit

• a source of energy

• conducting wires

• one or more loads that use the electric energy

switch

a device that controls the flow of current, which is added to the circuit

dry cell [diagram]

a source of energy that is represented by long and short parallel lines, where the longer line represents the positive

terminal and the shorter line represents the

negative terminal.

Connecting wires and zigzag line [diagram]

Connecting wires are shown as straight lines, while zigzag line represents a load or a resistor.

open switch and closed switch [diagram]

The symbol for an open switch is a broken line with one side lifted, while a closed switch is represented by a straight line connecting the terminals.

The two common types of circuit connections

series and parallel.

Series Circuit

An electric circuit in which the components are arranged to allow

current to flow through one single path is referred to as series circuit.

electric current ( I ) in a series circuit

The current in the circuit is constant. This means that the current in all parts of the circuit is the same.

Voltage (V) in a series circuit

The total voltage in the circuit is equal to the sum of the individual voltages across each component.

Equivalent Resistance (Req) in a series circuit

The equivalent resistance, Req, in a series circuit is equal to the sum of the individual resistances.

Parallel Circuit

In a parallel circuit, there are multiple pathways through which charges can flow.

Voltage in a parallel circuit

The total voltage supplied by the source is the

same across each individual branch.

Equivalent Resistance (Req) in a parallel circuit

The reciprocal of the equivalent resistance of resistors connected in parallel is equal to the sum of the reciprocals of the individual

resistances.

electric current ( I ) in a parallel circuit

The total current in a parallel circuit is equal to the sum of the currents in each branch.

how does a parallel circuit work

In a parallel circuit, the total current is distributed among the devices connected to the circuit. The amount of current passing

through each resistor depends on each resistance.