# Parallel Circuit Calculations 205

This class introduces the rules and formulas for parallel circuit calculations.

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## Class Details

Class Name:
Parallel Circuit Calculations 205
Description:
This class introduces the rules and formulas for parallel circuit calculations.
Version:
1.0
Difficulty:
Intermediate
Number of Lessons:
16
Spanish
Related 2.0 Class:
Parallel Circuit Calculations 311

## Class Outline

• Objectives
• Predicting Electrical Capacity
• Circuits
• Rules for DC Parallel Circuits
• Current in Parallel Circuits
• Voltage in Parallel Circuits
• Resistance in Parallel Circuits
• Determining Resistance: Resistors of Equal Value
• Determining Resistance: Product Over Sum
• Determining Resistance: Reciprocal Formula
• DC Parallel Circuit: Sample Problem
• Sample Problem: Calculating Voltage
• Sample Problem: Calculating Amperage
• Sample Problem: Calculating Power
• Combination Circuits
• Summary

## Objectives

• Describe the importance of predicting electrical capacity.
• Distinguish between the functions of series and parallel circuits.
• List the rules for DC parallel circuits.
• Describe current flow in parallel circuits.
• Describe voltage in parallel circuits.
• Describe resistance in parallel circuits.
• Use the resistors of equal value method to determine resistance in a parallel circuit.
• Use the product over sum method to determine resistance in a parallel circuit.
• Use the reciprocal formula to determine resistance in a parallel circuit.
• Calculate the resistance in a sample DC parallel circuit.
• Calculate the voltage in a sample DC parallel circuit.
• Calculate amperage in a sample DC parallel circuit.
• Describe combination circuits.

## Certifications

SME
• CMfgT
MSSC
• MSSC Maintenance Awareness

## Glossary

Vocabulary Term Definition
branch A portion of a circuit that contains a load, and as a result, values for current, voltage, and resistance. The values of each branch of a circuit determine the total applied values for current, voltage, and resistance.
capacity The amount of electricity that can safely flow through a wire without the wire overheating.
combination circuit A route for the flow of electricity that has elements of both series and parallel circuits.
control A part or component in a circuit that controls the flow of electricity.
current The flow of electricity. Current is measured in amps.
current adds A Kirchoff Law for DC parallel circuits stating that the total current of the circuit In a parallel circuit is the sum of the currents through each individual branch, regardless of the number of branches.
denominator The expression in the bottom location of a fraction, below the fraction bar.
direct current Current that travels in one direction. Direct current does not reverse the direction of flow.
inversely proportional A relationship where a number either increases as another decreases or decreases as another increases. Inversely proportional is the opposite of directly proportional.
Kirchoff Laws A set of universal truths established by scientist Gustav Kirchoff that govern circuit calculations.
load The part or component in a circuit that converts electricity into light, heat, or mechanical motion. Examples of loads are a light bulb, resistor, or motor.
Ohm's Law The universal truth stating that it takes one volt to push one amp through one ohm.
parallel circuit A route for the flow of electricity that has a branched path for each load. Parallel circuits do not require all loads to be switched on in order for the other loads in the circuit to function.
path A conductor that directs electricity in a circuit. The path is often copper wire.
power The rate at which a device converts electrical energy into another form, such as heat or light. Power is measured in watts.
product over sum method An equation for determining the total resistance for a parallel circuit. The product over sum method divides a pair of resistors, and then divides the result by another resistor, over and over again until only one pair is left.
reciprocal formula An equation for determining the total resistance for a parallel circuit. The reciprocal formula finds the total resistance of a parallel circuit by calculating the reciprocal of the sum of the reciprocals of the individual branches.
resistance The opposition to current flow. Resistance is measured in ohms.
resistor A device that restricts current flow and produces work, such as heat.
resistors of equal value method An equation for determining the total resistance for a DC parallel circuit with resistors that have the same value. The resistors of equal value method finds the total resistance by dividing the value of one individual resistor by the number of branches.
series circuit A route for the flow of electricity that has only one path. Series circuits are limited because, for any load to work, every load in the circuit must be switched on.
source The device that provides electrical power to a circuit. The source is the origin of electricity, such as a power plant.
voltage Electrical pressure that causes current flow. Voltage is measured in volts.
voltage drop The amount of voltage needed to push a given amount of current through a given amount of resistance.