How can energy change?

1. How can energy change? Chapter 5, Lesson 2 Pgs. 158-163

2. Lesson Objective I will know how energy changes form. I will know how electricity changes to light and gives off heat. Vocabulary Words: filament- a thin-coiled resistor that transforms electrical energy into heat and light energy. friction- a force that acts when two surfaces rub together. resistor- an object that uses energy in a circuit.

3. Energy Changing Form • There are many forms of energy-- electricity, light, sound, and energy of motion. • Energy is never lost. It cannot be made or destroyed. • Energy can transform, or change form. • Electricity can change to light. Motion can change to sound. Wind can change to electricity. • A lamp transforms electrical energy to light. • If you pluck a guitar string, the energy of motion transforms to sound energy.

4. Light from Electricity Televisions, computers, and light bulbs all use electricity. These objects are resistors that use the energy in a circuit. Most resistors transform electrical energy to heat and light. The filament inside a light bulb becomes so hot it glows, also giving off light.

5. Heat from Electricity When electrical current passes through a resistor, it often gives off heat. This change is why electrical wires sometimes become hot. The resistors of some appliances get so hot that they produce a red glow. This glow happens in toasters.

6. Lesson Summary Electrical, light, and energy of motion are some forms of energy. The energy of motion can cause friction and give off heat. Electrical energy can change to light energy and give off heat.