Light & Lens – How to burn a paper using a Convex Lens?

header image

L for Light & Lens

header image

Light is all around us. Yet, it is not often that we observe its properties. It can be fascinating to study how light travels and how a lens can change its path that can give a preliminary understanding of how light and lens inside our eyes make vision possible.

Tips to introduce

Warning: Adult supervision needed!

  • This experiment would require children to have a fair idea about sun rays, the streak of visible lines of light from the sun.
  • Allowing children to explore a real convex lens is recommended so that they understand what exactly a lens does.
  • Caution: The heat that converges through the lens can be so intense that it can burn the skin. Never leave the child unattended while doing the experiment.
  • Collect the things needed and when you are at the experiment venue, explain to them what you are going to do without revealing what you are likely to observe.
  • Set it up and let them observe what happens!

Things you’ll need

images of things needed - paper, a piece of wood, dry leaves and a convex lens

How do you do it?

1. Choose an open space where sunlight directly falls on a surface. A mid summer day is ideal for this experiment. I recommend to choose a place where you and children can have a shaded place that has an adjacent sunlit space for the experiment so that you all are safe from sun’s heat.

2. Place an ignitable material like paper, a piece of wood or dry leaves in the sunlit space. Hold a convex lens at a distance and angle such that sunlight directly passes through the lens and falls on the ignitable material on the other side.

3. Keep holding and depending upon the intensity of heat, you should start seeing smoke followed by burning in a few seconds to minutes.

The Science behind

A convex lens converges the light received from an object, sunlight in this case. When the light that is usually scattered in different directions is made to meet at a single point, the intensity of light and its heat multiplies many folds. As a result, the ignitable material that is subjected to the intense heat gets ignited.

Share your experience

Did you try? Did it work? Leave a word in the comment section. I would love to hear!

Here’s the full list of DIY Science Experiments in this series:

A for Air – Does Air has Weight?

B for Buoyancy – Can Egg float on Salt Water?

C for Capillary action – Rainbow Walking

D for Density – 3 Layer Density Experiment

E for Earth & Moon – Why does the Moon change its shape?: Phases of the Moon

F for Fire – Does Fire need Oxygen to Burn?

G for Gravity – Defying Gravity

H for Hot Vs Cold – DIY Water Temperature Experiment for Kids

I for Inside the Eye – How to see your Eye Blood Vessels?!

J for Jelly Egg – How to make a bouncy egg?

Leave a Reply