The Frightened Grasshopper: A Solar-Powered Robot Bug
Abstract"How do you frighten a grasshopper? And what does that have to do with light?" These are a couple of questions you're probably asking yourself after reading the title. Well, The Frightened Grasshopper Solar-Powered Bug is actually a toy grasshopper that vibrates when it is placed in sunlight or near a lightbulb. It stores up the energy from light, and converts it into motion. You will use this fun toy to explore how the brightness of the light affects the motion of the solar-powered insect.
David B. Whyte, PhD, Science Buddies
The objective of this electronics science fair project is to determine how varying the amount of light falling on the Frightened Grasshopper Solar-Powered Bug affects its level of movement.
In this electronics science fair project, you will build and test your own life-size robot grasshopper! The "Frightened Grasshopper" toy is an educational kit for the first-time electronics experimenter. It demonstrates how energy can be turned into different forms. First, radiant energy, which comes from the Sun or from a lightbulb, is turned into electrical energy by a small solar panel. A solar panel (solar means of or relating to the Sun) is a panel that produces either electricity or heat when light shines on it. Check out Kid's Info: Answers to Questions Frequently Asked by Kids! in the Bibliography, below, to learn more about turning solar energy into electrical energy. The electrical energy from the solar panel is then used to make a small motor spin. In other words, the electrical energy is converted into kinetic energy. Kinetic energy is defined as the energy of motion. The motor has a small weight on it, which is unbalanced, so when the motor is turned on, the unbalanced weight moves, making the grasshopper wiggle and move in circles. Lots of things around your house have motors in them, including your refrigerator, DVD player, hairdryer, and computer printer, to name a few.
In this electronics science fair project, you will vary the amount of light that hits the solar panel on the grasshopper and observe how this affects its activity. To do this, you will hold the grasshopper in your hand and bring it close to a lightbulb. You will measure how close the grasshopper has to be before the motor starts to spin. The goal is to measure how the bulb's wattage (which is the amount of power; higher wattage means more light and more radiant energy) affects the distance at which the grasshopper is activated. If you want to learn more about electricity in general, you can check out the Science Buddies Electricity, Magnetism, & Electromagnetism Tutorial.
Terms and Concepts
- Radiant energy
- Electrical energy
- Solar panel
- Kinetic energy
- Average, as in math
- What are the different parts of the "Frightened Grasshopper" toy?
- What is the area, in square centimeters, of the solar panel on the grasshopper?
- What is the definition of kinetic energy?
- What part of the toy converts electrical energy into kinetic energy?
- Energy Information Administration. (n.d.). Renewable Solar: Solar Basics. Retrieved May 6, 2015.
- Pacific Gas and Electric Company. (n.d.). Educational Resources-Students. Retrieved May 6, 2015.
- Harris, T. (2009). How Robots Work. How Stuff Works. Retrieved May 20, 2009.
- Rathjen, D. (2001). Watt's a Joule?. Retrieved May 22, 2009.
For help creating graphs, try this website:
- National Center for Education Statistics. (n.d.). Create a Graph. Retrieved May 20, 2009.
Materials and Equipment
- The Frightened Grasshopper Solar Kit, available from Jameco Electronics.
- Incandescent lightbulbs; 25, 60, 100, and 150 watts (W) (1 of each). This project will not work with compact fluorescent (CFL) or light-emitting diode (LED) bulbs.
- Lamp with a maximum wattage of at least 150 W (for incandescent bulbs) or 40 W (for CFL bulbs)
- Lab notebook
- Ruler, metric
- Cloth tape measure, metric
- Graph paper
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Preparing for Testing
Assemble the Frightened Grasshopper using the instructions that came with the toy. The parts that come with your kit are shown in Figure 1. Your completed grasshopper should look like the one in Figure 2.
- Because the toy is fragile and has some small parts, the assembly should be done with the help of an adult.
Figure 1. Parts for the Frightened Grasshopper robot kit.
Figure 2. An assembled solar-powered grasshopper.
- Make sure the grasshopper works by taking it outside and exposing it to bright sunlight. It should start to move when in the sunlight. See the video in the Introduction.
Performing the Experiment.
- Unplug the lamp.
- Put a 150-W incandescent lightbulb in the lamp.
- Plug it back in.
- Turn the lamp on.
Remove any sources of light, other than the lamp you are using.
- Turn off any other lamps in the area and block sunlight from entering the room.
- The room does not need to be very dark or pitch black. Just make sure there are no bright sources of light, other than the lamp.
Hold the grasshopper near the lightbulb, with the solar panel facing the lightbulb. The grasshopper should not be quivering yet.
- Try to keep the solar panel pointing directly at the lightbulb so that you get consistent results.
- Depending on the shape of your lamp, you may need to remove the lampshade to get close to the lightbulb. Use your judgment.
Have your helper measure the distance at which you're holding the grasshopper away from the lightbulb with the ruler and record the number (in centimeters, cm) in a data table, like the one below, in your lab notebook.
- Use the ruler to measure the distance. If the ruler is too short, use the cloth tape measure.
|Lightbulb Wattage||Starting Distance (cm)||Trial 1: Distance When Quivering (in cm)||Trial 2: Distance When Quivering (in cm)||Trial 3: Distance When Quivering (in cm)||Average (cm)|
- Move the grasshopper closer to the lightbulb, until it starts to quiver.
- Have your helper record the distance, in centimeters, at which the grasshopper started to vibrate, in your data table.
- Repeat steps 5–6 two more times to ensure your results are accurate and repeatable. Try to use the same starting position each time.
- Turn the lamp off and unplug it.
- Repeat steps 1–11 with the other three lightbulbs. You should have a total of three trials for each lightbulb.
- Repeat steps 1–12 two more times, so you have three data tables.
Analyze Your Data
- Calculate the average distance, as follows. Add the three trials within each data table for each lightbulb, and then divide by 3. Record the averages in your data tables.
Make a graph for each of your three test sets, either on paper, or using a website like Create a Graph.
- Put the wattage (25, 60, 100, and 150 W) on the x-axis.
- Put the average distance, in centimeters, on the y-axis.
- How did the wattage affect the grasshopper's movement? Think about what you could do to improve the procedure.
Ask an Expert
- Experiment with different kinds of colored plastic to see which block light from activating the grasshopper. This might be easier using filters over a flashlight.
- Take the grasshopper outside at 9:00 AM on a sunny day and place it on a flat surface in the sunlight. Record the number of times it spins around in 1 minute. Repeat this test every hour until it is no longer is activated by the sunlight. Graph the time of day on the x-axis and the number of rotations on the y-axis.
- Devise a way to make a sun-activated alarm clock from the grasshopper.
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