Astronomy Inquiry Lab: Light Sensor Investigation
Grade Level/Subject / High School (10th/11th/12th grade)Unit / Characteristics of Light
Enduring Understanding and Unifying Understandings / Stars are similar to living organisms in that the materials they are made out of and the processes they undergo are uniform, but they are all not physically alike and are continually undergoing development and maturing processes that alter their physical and orbital properties
1. Humans use science to organize their understanding of the natural world.
2. Our universe is composed of various forms of matter and energy that exist, interact, and change in a variety of ways.
3. Form and composition are related to function.
6. Patterns and cycles exist in nature.
SOL Objectives
Title / Light Sensor Investigation
Lesson Objective / Students will be able to understand how light intensity changes with distance according to the inverse squared law
Inquiry Level / 2
Materials Required / Lightbulb
Electronic device with LuxMeter app installed
Book or stand to attach device
Meter stick
Computer
Logger Pro
Student Handout
Name: ______Date: ______
LIGHT SENSOR INVESTIGATION
Investigating the Inverse Squared Law
To investigate how the intensity of light changes as distance changes between the sensor and light source.
1) Each lab group needs to download the free app LuxMeter on to their electronic device.
HOW DOES IT WORK? Light sensors take in the amount of photons hitting their surface.
2) Light sensor A and B (above) are identical in size and make. They are located in a room, with one light bulb as the “light source”. Looking at how many photo’s are hitting their surface, read the scenario. Predict the answers to the question in the last two columns based on the information given on how the sensors are set up (Scenario).
Scenario / Question / Logical Explanation / Which has the higher reading? (circle one)The sensors are in different rooms, and the same distance from the light source / What can we know about the light sources? / Light Sensor A
Light Sensor B
Not enough information
Sensors are in the same room, located at different distances from the light source / What do we know about the distances from sensor to light source? / Light Sensor A
Light Sensor B
Not enough information
Sensors are located in different rooms, with different light sources / What do we know about the distance and/or intensity of the light sources? / Light Sensor A
Light Sensor B
Not enough information
For this lab you will need: 2 meter sticks, light sensor, book/stand to attach light sensor to, working lightbulb, computer with logger pro
1) Tape two meter sticks to the lab table. Place your lightbulb at the “0 meter” mark.
2) Attach your light sensor to a book or stand, so that the sensor is at the same height off the table as your lightbulb.
3) Slide your light sensor (attached to the book or stand) along the meter stick, taking readings along the way. Be sure to take a WIDE VARIETY of data (not just really close, not just really far). Record your data in the chart below.
Distance (cm)Meter Reading
(lx)
4) Open “Logger Pro” on your computer. You need to enter in your data and make a best fit line to figure out how these two variables are related.
To make a best fit line:
a. In the left column (x), put your distances in cm. In the right column (y) , put your values for your light sensor in lx (which stands for lux).
b. Highlight all your data points in both columns.
c. Click on the “curve fit” button in your toolbar (see right)
(Directions continue next page)
d. Work your way through the first few “best fit” choices, clicking on “try fit” to see if it looks like it fits your data the best. When you have found the best line, click “okay”. (see below)
5) TEACHER CHECK: Have your teacher initial your graph. ______
What is the equation for your best fit line?
1) Why can’t we gather information about a star using a light meter, if we don’t know both it’s distance or size (brightness)?
2) Describe the curve generated by the data you graphed.
3) What does the curve indicate about the relationship between the apparent light intensity and distance?
4) If scientists can gain information about how much light is coming from a star to earth, what other information is important to be able to know size and intensity of the star? List two issues which may arise.
https://itunes.apple.com/us/app/luxmeter/id526675593?mt=8