Electricity/ Electronics/ Electrostatics

Generation of an induced voltage with permanent magnets

Principle

The students know that a current-carrying conductor is surrounded by a magnetic field which can cause mechanical movement in interaction with another magnetic field. They should demonstrate the reversal of this phenomenon, i.e. demonstrate that electr ...

Generation of an induced voltage with electromagnets

Principle

It is assumed that the students know that a voltage is induced in a coil, as long as the magnetic field contained by the coil changes.
When the induction process can be triggered by a permanent magnet, then this must also be possible with an el ...

The alternating current generator

Principle

The students are already well acquainted with a simple alternating current generator, the dynamo on their bicycle, whose working principle is to be worked out in this experiment. Technically, inner pole machines are used to generate high alternating ...

Voltage transformation

Principle

Transformers represent a significant application of induction. They are predominately used to transmit electrical energy over long distances with as little loss as possible, or to adjust fixed supply voltages to the rated voltages of electrical applia ...

Current transformation

Principle

When very high current strengths are required on a technical scale, e.g. for welding equipment or electric smelting furnaces, then so-called heavy current transformers are used. Their secondary coils have only a few turns of large diameter wire.
...

Self-induction when switching a circuit on

Principle

The students know that voltage is induced in a coil as long as the magnetic field inside the coil varies. They are familiar with electromagnets and, therefore, know that a coil with a current flowing through it produces a magnetic field and they know ...

Self-induction when switching a circuit off

Principle

In the last experiment, the students learned that self-induced voltage is formed in a coil when a direct current circuit is closed, and that this self-induced voltage counteracts the connected voltage. Now, they should learn that self-induced vol ...

Coils in alternating current circuits

Principle

The students know that self-induced voltage is generated in a coil in a direct current circuit when the circuit is closed or opened. They also know which direction the sel-finduced current has.
Based on this knowledge, they can probably pr ...

Earthing of the power supply line

Principle

Fatal accidents can occur when electrical appliances are handled in a household. Most of such accidents result from careless behaviour or lack of knowledge. The person model is to be used to demonstrate which parts of an electric circuit are extr ...

The protective conductor system

Principle

Faulty insulation can result in voltages on parts of appliances that are not intended to carry current.
Dangerous voltages occur most frequently on metal casings of electrical appliances. To exclude the possibility of danger to people using suc ...

The protective isolation transformer

Principle

When a separating transformer is used, there is no conductive connection between the primary circuit ("ring main") and the secondary circuit ("consumer circuit"). There is no voltage between the consumer circuit and earth. When a person touches a lead ...

The NTC resistor

Principle

In connection with Ohm's Law, the students have already learned that metallic conductors generally have a resistance which increases with increasing temperature.
Now, they should discover that the opposite is true for NTC resistors (N

The PTC resistor

Principle

In connection with Ohm's Law, the students have already learned that pure metallic conductors have a resistance which increases with increasing temperature.
PTC resistors (Positive Temperature C

The light dependent resistor

Characteristic curve of a Zener diode

Principle

Zener diodes are silicone diodes with a high level of p and n area doping. They behave like normal Si-diodes in the forward direction. Voltage connected in the reverse direction produces a strong electric field in the barrier layer. When the volt ...