Electricity

The bimetallic switch

Principle

A bi-metal strip comprises two metal strips which are laminated together and have different thermal expansion coefficients. When warmed the strip flexes toward the side with the lower expansion coefficient. In so doing, it can act as a switch in the el ...

Conversion of electrical energy into mechanical energy

Principle

A motor that raises a load, i.e. converts electrical energy into mechanical energy, is a familiar everyday sight. The special feature of this set-up is that it can be used to generate electrical energy again directly from the descending weight. That electrical e ...

Self-induction when switching a circuit on

Principle

A coil is located in a DC circuit. When the circuit is closed, the magnetic field of the coil builds up and generates a self-induction voltage which counteracts the increase.  An incandescent lamp in the circuit lights up only gradually.

Solar cells

Resistance of wires - dependence on the length and cross-section

Principle

The resistance of a short thick wire is different to that of a long thin one.

Tasks

Examine how the value of the resistance of a wire depends on its length and cross-sectional area.

Current and resistance in a parallel connection

Principle

In households, electrical devices are often connected in parallel to different sockets of the same electric circuit. The total current and the total resistance of the circuit can be predicted from the partial resistances.

Tasks

Current and resistance in a series connection

Principle

Various components in a circuit can be connected in series. The total resistance and the total current can be calculated from the partial resistances of the components.

Tasks

• Switch an incandescent lamp in se ...

The potentiometer

Principle

Many controls on electrical devices are potentiometers. A potentiometer acts as a voltage divider. It corresponds to a series connection of two variable resistors with a centre tap, whereby the sum of the resistance of the two resistors remains consta ...

Electrical power and work

Principle

A greater number of lamps means more power than a smaller number of lamps. How much voltage and current do you need for the many lamps? Which conclusions on electrical power and work can you drawn from this?

Tasks

...

Charging and discharging a capacitor

Principle

Capacitors are devices that can store charge. Here the details of how the charge gets in and out of the capacitor is looked at.

Tasks

Examine the behaviour of the voltage and current of a capacitor during the charg ...

Diodes as electrical valves

Principle

A diode only allows electric current to pass in one direction and blocks the other one to the current. It therefore acts as an electric valve. This enables alternating current to also be usable to pump charge into a capacitor.

Tasks< ...

Diodes as rectifiers

Principle

A diode only allows current to flow in one direction and blocks the flow of itin the other direction. So the current can flow only during a half wave through a diode in an alternating current circuit.

Tasks

Measure ...

The transistor as a switch

Principle

The development of computer engineering and the increasing digitalisation in the transmitting and processing of information are accompanied by an increasing use of transistors for switching functions.

This experiment is designed to demonstra ...

The permanent magnet DC motor

Principle

Electric motors for not too high power and simple dynamos are frequently based on the basic principle that an electromagnet rotates in the field of a permanent magnet (or several of them).

Tasks

Examine the behavio ...

The series motor

Principle

The stator field of an electric motor can be generated by an electromagnet, which is then called the excitationwinding. In series motors, the excitation winding is switched in series with the armature winding of the rotor.This type of motor is sometim ...