Understanding Electricity

7th Grade Science

Essential Standards Break-out Session

1-3-12

Desired Outcomes

• 1. To introduce you to the electricity standard.

• 2. To add to your knowledge base about electricity.

• 3. To clear up any misconceptions.• 4. To provide a strategy for teaching

electricity to your students.

• 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.

• Energy can be transferred from one system to another (or from a system to its environment) in different ways: 1) thermally, when a warmer object is in contact with a cooler one; 2) mechanically, when two objects push or pull on each other over a distance; 3) electrically, when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device; or 4) by electromagnetic waves. Energy is one of the fundamental building blocks of our universe. Energy can change from one form to another, although in the process some energy is always converted to heat. Some systems transform energy with less loss of heat than others. Electrical energy can be produced from a variety of energy sources and can be transformed into almost any other form of energy. Batteries store energy and transfer energy to components in a circuit. In the battery the energy comes from chemical reactions. 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. The electrical energy generated by windmills, waterfalls and power plants is actually a secondary source of energy. To produce electricity, a heat source is needed to create the conditions in which electrical currents form. In effect, the primary source of electrical energy is the heat generated by burning fossil fuels, water power and wind power. A natural form of electrical energy can be seen in the lightning that appears during storms. Solar energy, water and wind power are sources of green energy—meaning they do not pollute the environment.

Your needs:

Safety

• D-cell• Wire • Touch the + and – ends of the D-cell with

the wire

• Let go when it gets hot

Using a 1.5 Volt D-cell

• Will not– Shock you– Hurt you

– May get hot if you connect just a wire to the D-cell

• Be careful of sharp points on wires

Warn students against

• Any contact with electrical outlets• Never put anything into an electrical

outlet• If the wires and D-cell heat up, let go

A mini-lesson on electrons

• Your students in 7th grade DO NOT need to know this….

Atoms

• Make up everything• Comprised of smaller parts• Protons – in the center of the atom,

positively charged• Neutrons – in the center of the atom,

neutrally charged• Electrons – outside the nucleus,

negatively charged

When talking electricity

• What part of the atom is involved?• Why?

When electrons move

• They carry energy from one place to another– The “battery” (collection of cells) or D-cell

(single cell) provides the energy to push the electrons.

Potato Clock

• 2 different metals in something that is an acid

• Metals react differently– Creates a + on one side– Creates a – on the other side

– + is attracted to – much like N is attracted to S; soooooo electrons flow

• Use 2 wires, a bulb and a D-cell to make the lightbulb light– Draw your prediction before you begin

– Student handout

• Must have a complete circuit for electrons

Examine the bulb

• Light the bulb with only one wire and a D-cell

Circuit

• A complete path for electrons to flow

Conductors must be used with electricity

• Test items to see which are conductors

• All metals are conductors– Things that contain electrolytes in liquids are

also conductors• examples: lake water (not pure water), lemon

juice -

Using holders to make circuits easier

• Made of conductors and insulators• Must touch all parts of the circuit to the

metal of the holder for the circuit to work

Will not work. Why?

Troubleshooting

• May need to strip insulation from the ends of the wires

• Bulbs may not be touching both the sides and the bottom of the holders

Keep your D-cells from becoming “dead”

• Use a switch

Open circuit – turns off electricity

Closed circuit – turns On electricity

Series circuits

• One big loop

Parallel circuits

• Many loops side-by-side

Other topics ???

• 1. To introduce you to the electricity standard.

• 2. To add to your knowledge base about electricity.

• 3. To clear up any misconceptions.• 4. To provide a strategy for teaching

electricity to your students.

Your needs