How to measure the speed of light with a chocolate bar?
23/05/2024Theory
Although it may seem surprising, the speed of light can be measured with a simple experiment, using a chocolate bar and a microwave.
To begin with, the speed of light, estimated to be approximately 299,792 kilometers per second in a vacuum, is a fundamental constant in physics. According to Einstein’s theory of relativity, the speed of light in a vacuum is the upper speed limit for any object or signal in the universe.
Furthermore, this constant not only plays a crucial role in theoretical physics but also has practical implications in everyday life and various technologies such as fiber optic networks. Similarly, this constant is essential in GPS systems, where the precision in measuring the speed of light makes it possible to determine locations with great accuracy.
Moreover, the speed of light plays a crucial role in the way we observe the universe. Light from distant stars and galaxies takes years, even millions of years, to reach us. Consequently, when we observe the universe, we are actually looking into the past [1].
Materials needed for the experiment
- A microwave oven.
- A bar of chocolate.
- A ruler.
Steps
- Remove the turntable from the microwave.
- Place the chocolate bar inside the microwave oven and heat it long enough for it to start melting in a few spots.
Note: the microwave oven heats the food using electromagnetic waves with a certain wavelength. The melted spots on the chocolate correspond to the points of maximum intensity called “nodes”. - Measure the distance between the two spots of the chocolate bar with the ruler, and you will obtain the wavelength of the microwaves in the microwave oven.
Calculations
The microwave frequency is usually indicated in the manual of the device or on a label attached. By multiplying the wavelength and the frequency, you can calculate the speed of light.
Final step is to substitute the value of the frequency for “f” of the equation, and the value measured with the ruler (in meters), for “lamda” of the equation. The result will be close to the value we know for the speed of light [2]:
This experiment will give you an excuse to have some chocolate while introducing relativistic physics. This experience combines learning and surprise, demonstrating that science is everywhere, even in a microwave oven.