Cobra4

Photosynthesis

Principle

This experiment shows that carbon dioxide is consumed during photosynthesis, whereas it is produced through cellular respiration.

Pulse at rest and during exercise

Principle

Exercises change the frequency of our pulse. The difference between a pulse at rest and a pulse after exercise will be studied in this experiment.

How much air can our lungs contain?

Principle

Lungs are organs which enable carbon dioxide (CO2) to be exhaled and oxygen (O2) to be absorbed. Contraction of the diaphragm connected to the lungs causes them to stretch so that air is drawn into them from the surroundings. When the diaphragm subseq ...

Direct determination of lung volume from a spirogram

Principle

The lung is the organ which plays a decisive role in the exchange of gases with the surroundings. The membrane with which the lung is lined releases CO2 from the blood in which it is dissolved and passes O2 into the blood. To breathe in, the diaphrag ...

Does the lung volume depend on how tall you are?

Principle

In this experiment, you are to determine if lung volume is dependent on gender or on how tall you are.
For this, you are first to measure your vital capacity (VC) using a spirometer. Following this, you are to
separate the measured values ...

Which method enables lung illnesses to be diagnosed?

Principle

The forced expiratory volume (FEV) in one second is used in the diagnosis of lung illnesses. For the measurement of this here, the student carrying out the test breathes normally a few times, presses out all the air he or she can, takes a deep breath ...

Why do energy-saving lamps need some time to achieve fullbrightness?

Principle

Energy-saving lamps (compact fluorescent lamps) are increasingly replacing customary filament lamps. They have the characteristic that they need a longer time until their light reaches full brightness, because their brightness is temperature dependent ...

Why do light bulbs burn out mostly when being turned on?

Principle

You know it all too well: You turn the light on and nothing happens except perhaps a pop! This experiment explains why filament lamps "burn out" and why it almost always happens when they are turned on.

Floating and sinking

Principle

The buoyancy force is equal to the force of the weight of the liquid displaced: This experiment uses the archimedean principle to determine to which extent the buoyancy depends on the mass and volume of a body and the density of the liquid, using ever ...

Altitude measurement on a trail

Principle

The altitude profile of a hiking trail or route to school can be measured during a school trip or as an exercise for the students. The altitude profile can also be used to demonstrate that the atmospheric pressure decreases when the altitude increases ...

Measuring the height of a tower

Principle

The weather sensor can be used to determine the height of a tower as a function of the change in air pressure with the aid of the barometric formula.

Terrain mapping

Principle

The drawing of maps is one of the favourite tasks of the students during geography lessons and of a high didactic value. The altitude measuring function of the Cobra4 Sensor-Unit "Weather" is a userfriendly tool which provides altitude values so that ...

What happens during the flash recycling time of a camera?

Principle

You experience it with both digital and analogue cameras: You want to take a photo but it often takes several seconds until the flash is "loaded". This experiment illustrates what happens in that time and why it takes so long: The behaviour of the cur ...

Why do mobile phones or laptops need a charger/adapter?

Principle

In this experiment, the generation of alternating voltage and the conversion of it to direct voltage by means of rectifying and smoothing are presented.

An alternating voltage changes polarity periodically. The electricity network supplies a ...

How can ships made of steel float on water?

Principle

Everyone has at one time or another wondered how comes that ships made of steel can float on water but a steel ball simply sinks. Expanded bodies have the property of having less weight in water than in air, as one notices when one swims, for example. ...