14.1 Series Circuits Swaney

Objectives 1. Describe a series circuit. 2. Calculate the resistance and current in a series circuit. 3. Explain how voltage changes across each resistor in a series circuit.

What is a series circuit? Series circuit- contains only one path for current to flow Current is the same at all points in the circuit. Example: Inexpensive strings of holiday lights.

What would happen if you turn the switch to the OFF position? Would all the lights go out?

How do dimmer switches (potentiometers) work in series circuits?

Resistance in series circuits Every time you add a light bulb to the circuit, you add resistance. To find the total resistance, you add the individual resistances together.

Adding resistance is like adding pinches to a hose. The water flow represents the current.

Ohm’s Law I=V/R You can calculate current (I) if you know voltage and resistance

Remember: Energy can never be created or destroyed. Devices in a circuit convert electrical energy carried by current into other forms of energy. As each device uses power, the power carried by current is reduced. As a result… Voltage drop-voltage gets lower after each device that uses power.

As power gets used, voltage gets lower.

How to measure voltage drop.

Because energy is never created or destroyed…. The total of all voltage drops must add up to the battery’s voltage. This is known as Kirchhoff’s voltage law (named after German physicist Gustav Robert Kirchhoff )

14.1 Section Review 1.What do you know about the current at different points in a series circuit? 2.Three bulbs are connected in series with a battery and a switch. Do all of the bulbs go out when the switch is opened? Explain. 3.What happens to c circuit’s resistance as more resistors are added in series? 4.A series circuit contains a 9-volt battery and three identical bulbs. What is the voltage drop across each bulb?