🧪 Science with Sarah:💡 Index card flashlights

Help your kiddos understand circuits!

Learn how to make index card flashlights at home with Meteorologist Sarah Spivey and her awesome assistant, David Sears!

👉 Watch the video of Sarah’s school science experiment here!

Hello parents, teachers and students! Are you looking for something fun to do at home that has a little bit of science behind it? Learn how to make index card flashlights at home with Meteorologist Sarah Spivey and her awesome assistant, David Sears!

Be sure to check out GMSA@9 on Wednesdays when Meteorologist Sarah Spivey does the demonstrations and explains the science behind it.

Science with Sarah: Invite KSAT to your school for live science experiments. (KSAT)

HERE’S WHAT YOU’LL NEED

You'll need aluminum foil, an index card, a mini LED lightbulb, a button 3V battery, and file folder labels (Copyright 2022 by KSAT - All rights reserved.)

DO THE EXPERIMENT

  • STEP 1: Start by locating the positive wire on the LED bulb. It’s the longer of the two wires.
  • STEP 2: Using a small piece of file folder label, tape the LED bulb to the index card, leaving plenty of room at the bottom of the wires. Make sure you leave plenty of the wires exposed so that they can make good contact with the aluminum foil, which will be the conductor for our flashlight. On the index card, mark which side of the card contains the positive wire and which side of the card contains the negative wire. See figure below.
Make sure to leave parts of the wire exposed and label the positive and negative sides on the index card (Copyright 2022 by KSAT - All rights reserved.)
  • STEP 3: Take a piece of aluminum foil and fold it over “hotdog” style so that you end up with a skinny, long piece of aluminum foil
Make a skinny, long piece of aluminum foil. This will be our conductor (Copyright 2022 by KSAT - All rights reserved.)
  • STEP 4: Tape one end of the aluminum foil to the positive end of the LED light bulb. Then tear or cut the aluminum foil strip so that about the bottom third of the index card it not covered with aluminum foil
Tape one end of the aluminum foil to the positive end of the LED light bulb. Then tear or cut the aluminum foil strip so that about the bottom third of the index card it not covered with aluminum foil (Copyright 2022 by KSAT - All rights reserved.)
  • STEP 5: Place the button battery, positive side down onto the aluminum foil strip. Using two pieces of a file folder label, tape the battery to the index card. Make sure to leave some of the textured, negative side of the battery exposed. See image below.
Place the button battery, positive side down onto the aluminum foil strip. Using two pieces of a file folder label, tape the battery to the index card. Make sure to leave some of the textured, negative side of the battery exposed. See image below. (Copyright 2022 by KSAT - All rights reserved.)
  • STEP 6: Flip the index card. On the negative side of the index card, tape the remainder of the aluminum foil strip to the negative wire of the LED bulb.
Flip the index card. On the negative side of the index card, tape the remainder of the aluminum foil strip to the negative wire of the LED bulb. (Copyright 2022 by KSAT - All rights reserved.)
  • STEP 7: Complete the circuit and turn on the bulb by bringing the longer piece of aluminum foil into contact with the battery on the other side of the index card. Your lightbulb should turn on!
Complete the circuit and turn on the bulb by bringing the longer piece of aluminum foil into contact with the battery on the other side of the index card. Your lightbulb should turn on! (Copyright 2022 by KSAT - All rights reserved.)

HOW IT WORKS

This is a great example of how circuits work and it shows that aluminum foil is a good conductor of electricity!

The positive side of the index card is charged by the positive side of the battery. However, the lightbulb doesn’t turn on until the circuit is completed. This happens when other side of the index card comes in contact with the negative side of the battery through the conductive aluminum foil.

If you find that the lightbulb is not turning on, try some troubleshooting. First, make sure enough of the textured, negative side of the battery is exposed (Step 5). Second, make sure that enough of the lightbulb wires are coming in contact with the aluminum foil (Step 2).

SCIENCE WITH SARAH

If you’d like Sarah and David to come to your school and conduct a science experiment live on KSAT, email sciencewithsarah@ksat.com.

Parents and guardians: upload a video of your child performing the activity by clicking here. Send it in and you might see it on GMSA @ 9 a.m.!


About the Authors:

Sarah Spivey is a San Antonio native who grew up watching KSAT. She has been a proud member of the KSAT Weather Authority Team since 2017. Sarah is a Clark High School and Texas A&M University graduate. She previously worked at KTEN News. When Sarah is not busy forecasting, she enjoys hanging out with her husband and cat, and playing music.

Ben Spicer is a digital journalist who works the early morning shift for KSAT.