Electrical Circuits

Electrical Circuits

I CAN...

1. Recognize that energy can be transferred by a force over a distance (work).
2. Identify the parts to complete an electrical circuit.

Learning Targets & Standards

• 7.P.2: Understand forms of energy, energy transfer and transformation and conservation in mechanical systems.

• 7.P.2.3 Recognize that energy can be transferred from one system to another when two objects push or pull on each other over a distance (work) and electrical circuits require a complete loop through which an electrical current can pass.

Types of Energy Transfer

Energy can be transferred from one system to another (or from a system to its environment) in different ways:

1.)Thermal 2.)Mechanical

3.)Electrical 4.)Electromagnetic waves

Thermal Energy

• When a warmer object is in contact with a cooler one

Mechanical Energy

Two (2) objects push or pull on each other over a distance

Electrical Energy

• Electrical energy can be produced from a variety of energy sources and can be transformed into almost any other form of energy.

• An electrical source such as a battery or generator is connected in a complete circuit to an electrical device.

Electrical Energy Reading

A natural form of electrical energy can be seen in the lightning that appears during storms.

Take about 7 minutes to access the link below to review what electrical energy is and examples of different ways to generate electrical energy every day.

https://www.solarschools.net/knowledge-bank/energy/types/electrical

Electrical Energy Review

• In effect, the primary source of electrical energy is the heat generated by burning fossil fuels, water power and wind power.

• The electrical energy generated by windmills, waterfalls and power plants is actually a secondary source of energy.

• Solar energy, water and wind power are sources of green energy—meaning they do not pollute the environment.

• To produce electricity, a heat source is needed to create the conditions in which electrical currents form.

Multiple Choice

How does a wind turbine produce electricity?

• It releases kinetic energy to the wind.

• It releases potential energy to the wind.

• It converts the wind's kinetic energy to mechanical energy.

• It converts the wind's potential energy to mechanical energy.

Electromagnetic waves

Energy in waves

Energy Transformation & Energy Transfer

• Energy can change from one form to another (transformation) although in the process some energy is always converted to heat.

• Some systems transform energy with less loss of heat than others.

• Batteries store energy and transfer energy to components in a circuit. In the battery the energy comes from chemical reactions.

Energy Transformation

• *You can see the idea of energy transformation when you think about lighting a match. What happens is that the chemical energy stored in the match is converted into heat energy and light energy.

• *When electrical energy passes through a light bulb, electrical energy is transformed into light energy. 

Multiple Choice

A student wants to use the diagram below to explain what happens when the light bulb turns on. How could she best explain what is happening?

• Light energy is transformed to electric energy.

• Electric energy is transformed to light energy.

• Electric energy is transformed to motion energy.

• Motion energy is transformed to electric energy.

Multiple Choice

Which of the following energy transformations occur when a lamp is plugged into the outlet and the bulb is inserted into the lamp?

• thermal - electrical - light

• electrical - light - thermal

• light - thermal - electrical

• electrical - thermal - light

Multiple Choice

Two friends decide to go to the park and watch a movie on a computer. The computer runs on battery power. What energy transformation is occurring from the battery to the light being given off by the computer?

• chemical - light - sound

• mechanical - chemical - electrical

• mechanical - electrical - light

• chemical - electrical - light

Electrical Energy

Electricity is important because we can use it to make so many things work (electrical energy). For example, a bulb converts electrical energy into light energy and a speaker converts it into sound energy.

Multiple Choice

10. A lamp begins with electrical energy when plugged in and turns into _________ energy when the light comes on.

• Mechanical (PE + KE)

• Kinetic

• Radiant (Light)

• Sound

Electric Circuits

• Electricity is the presence or movement of electrons, which are tiny, negatively charged particles that orbit an atom’s nucleus. Electricity is what we get when electrons move from one place to another. 

• Energy can be transferred from one system to another when two objects push or pull on each other over a distance. In the case of electricity, electrons are pushed and pulled through a circuit

Electric Circuits

• In order for electricity to be useful in our homes and devices, there needs to be a steady flow of electrons called a current. 

• There also needs to be a complete circuit or a complete loop through which the electrical current can pass.

Electric Circuits

• In a complete circuit, energy starts at a power source (for example a battery), moves through a conductor (for example, a metal wire), passes through a load (a device that uses electricity such as a light bulb or toaster) and returns back to the power source.

• It starts out in one place, travels around the circuit, and ends up back at the place where it originated. The electrons are pushed and pulled through the circuit.  

Batteries and Circuits

• Batteries are devices that use “energy transformation” to produce electricity. They work by changing stored chemical energy into electrical energy.

• A chemical reaction inside a battery creates electrons. These electrons are stored in the negative terminal (-) of the battery.

• When a battery is part of a complete circuit, the negative terminal pushes the electrons out.

• The electrons travel from the negative terminal, through the circuit to the positive terminal (+). The positive side of the battery pulls the electrons in.

Multiple Choice

A person enters a room, flips the light switch, and a lamp turns on. What causes the lamp to turn on?

• The circuit is open, and flipping the switch closes the circuit.

• The circuit is closed, and flipping the switch opens the circuit.

• The wires are connected, and flipping the switch disconnects the wires.

• The wires are connected, and flipping the switch disconnects the lamp.