Fun and easy science experiments for kids and adults.

Death ray

Use a magnifying glass to collect the Sun's rays and melt chocolate. This experiment will show you how much energy there is in sunlight.

Gilla:		Dela:

Video

Materials

1 magnifying glass
1 saucepan
1 piece of chocolate
Sunny weather
Safety equipment: 1 pair of sunglasses, 1 fire extinguisher

Warning!

Wear sunglasses during this demonstration. The light reflected from the chocolate becomes very strong.
In this demonstration, there may be fire. A fire extinguisher must be available.
Never set fire to anything but the chocolate.

Step 1

Go outside and place the saucepan on the ground. Put the chocolate in the saucepan.

Step 2

Put on your sunglasses. Hold the magnifying glass between the piece of chocolate and the Sun, as if the Sun were to "look" at the piece of chocolate.

Step 3

Adjust the distance between the magnifying glass and the piece of chocolate so that a dot of light, as small as possible, forms on the piece of chocolate.

Step 4

Now keep that dot of light in the same place. See how the chocolate melts and burns!

Short explanation

The magnifying glass collects and focuses the sunlight on a small area. Some of the sunlight's energy is absorbed by the chocolate, which causes its temperature to increase and it melts. This demonstration shows in a fairly effective way how dangerous the Sun's rays can be.

Long explanation

The Sun is the name of the star around which Earth orbits. The Sun is enormous compared to Earth. Its diameter is 109 times that of Earth and its mass is 99.9 % of the total mass of the solar system.

In the nucleus of the Sun, something called fusion takes place, which means that atomic nuclei merge. More specifically, hydrogen nuclei merge into helium nuclei, and in this process, lots of electromagnetic radiation is released. This electromagnetic radiation seeks its way through the Sun and then leaves its surface. A fraction of this radiation reaches Earth. The electromagnetic radiation has many different wavelengths, and radiation with certain specific wavelengths has different names. The three types of electromagnetic radiation that mainly penetrates the atmosphere are infrared radiation, visible light and ultraviolet radiation (visible light is the electromagnetic radiation we humans have the ability to see).

When the electromagnetic radiation reaches Earth's surface, some of it is absorbed. When this happens, Earth's surface heats up. What happens physically is that the electromagnetic energy of the radiation is converted into kinetic energy of the particles that make up Earth's surface. The more these particles move, the warmer Earth's surface is.

A magnifying glass has a convex lens that directs the electromagnetic radiation from the Sun to a single point. This point absorbs a lot of electromagnetic energy and can become very hot. When the temperature gets high enough, atoms begin to react with each other in chemical reactions - it burns.

Experiment

You can turn this demonstration into an experiment. This will make it a better science project. To do that, try answering one of the following questions. The answer to the question will be your hypothesis. Then test the hypothesis by doing the experiment.

What happens if you increase or decrease the distance between the piece of chocolate and the magnifying glass?
What is the temperature of the chocolate after being exposed to the death ray different amounts of times?
What is the strength of the death ray during a clear sky compared to a cloudy sky?
What is the effect of the death ray on different objects (a marshmallow, butter, paper, a match, a balloon etc.)?
What happens if you use two magnifying glasses?
How can you make the strongest death ray?