resistors in series or in parallel chapter 20 section 2

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Resistors in Series or in Parallel Chapter 20 Section 2

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Page 1: Resistors in Series or in Parallel Chapter 20 Section 2

Resistors in Series or in Parallel

Chapter 20 Section 2

Page 2: Resistors in Series or in Parallel Chapter 20 Section 2

Single Resistor Alone

In a circuit that consist of single bulb and a battery, the potential difference across the bulb equals the terminal voltage.

The current can be found using Ohm’s Law if the resistance is known.

Page 3: Resistors in Series or in Parallel Chapter 20 Section 2

Series

Series – Describes a circuit or portion of a circuit that provides a single conducting path without junctions.

Charges that pass through one resistor must pass through the second resistor and then the third and so on.

All charges follow the same path then it is said to be connected in series.

Page 4: Resistors in Series or in Parallel Chapter 20 Section 2

Series Circuit Diagram

Page 5: Resistors in Series or in Parallel Chapter 20 Section 2

Conservation of Charge

According to conservation of charge, the amount of charge that enters a resistor must equal the amount of charge leaving the resistor.

Resistors that are connected in series, the current in each resistor is the same.

Page 6: Resistors in Series or in Parallel Chapter 20 Section 2

Total Resistance

Equivalent Resistance – The total resistance of the circuit.

The equivalent resistance in a series circuit is the sum of the circuits resistance.

The equivalent resistance can then be used to find the current in the circuit as long as the voltage is known.

Page 7: Resistors in Series or in Parallel Chapter 20 Section 2

Resistors in Series Equation

Req = Equivalent ResistanceTo find the total current in a series

circuit, first simplify the circuit to a single equivalent resistance

Page 8: Resistors in Series or in Parallel Chapter 20 Section 2

Potential Difference Across Resistors

The potential difference across each resistor is different.

The current across each resistor is constant.

V1 = IR1

V2 = IR2

V3 = IR3

Page 9: Resistors in Series or in Parallel Chapter 20 Section 2

Why Use Series Circuits?

Resistors placed in series can regulate the current in a device.Lots of resistors will make the current

very low.This is why Christmas lights are in series

so the filament doesn’t have to withstand high currents which could cause fires.

Several lesser resistors can make one large equivalent resistor which may not be available.

Page 10: Resistors in Series or in Parallel Chapter 20 Section 2

Parallel Circuits

Parallel – Describes two or more components in a circuit that are connected across common points or junctions, providing separate conducting paths for the current.

The advantage to parallel circuits is that if one of the lights on a strained go out, the rest of the lights remain lit.

Page 11: Resistors in Series or in Parallel Chapter 20 Section 2

Parallel Circuit Diagram

Page 12: Resistors in Series or in Parallel Chapter 20 Section 2

Resistors In Parallel & Voltage

Resistors in parallel have the same potential difference across them.

The current across the resistors vary on the strength of resistance.

Page 13: Resistors in Series or in Parallel Chapter 20 Section 2

Resistors in Parallel Equation

1𝑅𝑒𝑞

=1𝑅1

+1𝑅2

+1𝑅3

+…

Page 14: Resistors in Series or in Parallel Chapter 20 Section 2

Resistors in Series or in Parallel

Circuit Type Series Parallel

Schematic Diagram

Current=Same for each resistor

= Sum of currents

Potential Difference (Voltage) =Sum of voltage =Same for each

resistor

Equivalent Resistance =Sum of individual

resistors=Reciprocal sum of resistors