A flashlight is a portable, battery-operated device that produces light. A typical handheld flashlight consists of one or more batteries inside a compartment that forms the handle of the light. There is a switch between the batteries and the bulb. The switch controls the flow of electricity between the batteries and the bulb.
Flashlights have multiple uses. We use them during emergencies such as power outages or when our car breaks down. Our parents may use them while searching through the attic, the basement, or a dark closet. You may have used one on a camping trip or when you walked down the street while trick-or-treating. Everyone has used a flashlight at one time or another. When we do, energy is transformed.
Energy is the ability to do work or cause a change. The law of conservation of energy states that energy cannot be created or destroyed, but it can be transformed from one form to another. There are many different forms of energy, such as chemical energy, electrical energy, and light energy.
What energy transformations occur when we use a flashlight? First, the batteries contain chemical energy. This is energy that will be released during a chemical change. When chemical bonds are formed or broken, electrons are rearranged. This movement of electrons produces chemical energy. Batteries can convert stored chemical energy into electrical energy.
Electrical energy is the energy of electricity. When electrical charges move through a conductor, it is called electricity. Electricity moves through wires to places where it is needed. Then it can be converted into other forms of energy. In a flashlight, the electrical energy becomes light energy and thermal energy in the bulb.
Light energy moves by wave motion. That is, light is a form of energy caused by electromagnetic waves. It enables us to see, since objects are only visible when they reflect light into our eyes. Our eyes convert the light energy back to electrical energy. They make a nerve signal that our brain can convert into an image we see.
Thermal energy is the energy of heat. When energy transforms from one form into another, a small amount is often converted into thermal energy as a byproduct. The bulb transforms electrical energy into both light energy and thermal energy. It makes more light than heat, however. This is why the light bulb starts to feel warm after the flashlight has been on for a while.
The last time you looked at a flashlight, it probably looked pretty simple. You flip the switch, and light comes out. Now you know that there is much more happening. Energy must first be converted from chemical energy in the batteries into electrical energy. Then this energy moves to the bulb to be transformed into the light you see.
QUESTION 1
Which of the following sentences is the best short summary for a flashlight?
OPTIONS
A flashlight has many uses.
A flashlight is able to create light energy, allowing us to see in the dark.
A flashlight is a necessary tool for every household.
A flashlight is a portable, battery-operated device that makes light.
QUESTION 2
Much like a battery, wood contains stored energy. What energy transformations occur when wood is burned?
OPTIONS
Thermal energy transforms to chemical energy and light energy.
Biological energy transforms to electrical energy and light energy.
Chemical energy transforms to thermal energy and light energy.
Chemical energy transforms to thermal energy and heat energy.
QUESTION 3
Based on the context of the passage, what does converted mean?
OPTIONS
Transferred
Changed
Transported
Current
QUESTION 4
Identify the correct order for the energy transformations in a flashlight.
OPTIONS
Electrical to chemical to thermal
Light to electrical to chemical
Thermal to electrical to light
Chemical to electrical to light
QUESTION 5
In an ideal situation where no heat energy is produced, what is the relationship between the chemical energy provided by the battery and the electrical energy produced according to the law of conservation of energy?
OPTIONS
The chemical energy should be less than the electrical energy.
The chemical energy should be equal to the electrical energy.
The chemical energy should be more than the electrical energy.
None of the above.
The correct answer for question 1 is: A flashlight is a portable, battery-operated device that makes light.
The correct answer for question 2 is: Chemical energy transforms to thermal energy and light energy.
The correct answer for question 3 is: Changed.
The correct answer for question 4 is: Chemical to electrical to light.
The correct answer for question 5 is: The chemical energy should be equal to the electrical energy.