Demonstraton Electric Bell

Description

Students can explore how a simple electric motor works by doing a series of investigations. This St. Louis motor can be adjusted so students can study the effect of voltage and position of the brushes on the commutator. The motor consists of a two pole DC armature. The brush holder, with two heavy binding post terminals, can be rotated for experiments. The permanent bar magnets, supported by clamps, can be adjusted to the desired location. This apparatus requires 4 D cell batteries with holder (not included) or a power supply and two connecting leads (not included).

Description

This apparatus is an effective demonstration of how the earth wire and fuse act together to protect both the user and the appliance. When the appliance is connected correctly and the LEDs in the appliance will illuminate to show the appliance is working. A fault is then demonstrated by swapping the live wire from inside the appliance to the case to show either the fuse melts (protecting the user and appliance) or in the case of no earth wire, the LEDs illuminate to indicate the passage of current through the person to ground. The fuse is easily visible and can be seen to ‘blow’ when a fault occurs.The unit is supplied with 10 m of fuse wire and full instructions. A 12 V DC power supply is required. Connections are made via 4 mm shrouded sockets.

Description

The motor consists of a two pole armature mounted between the ends of two bar magnets. The armature has a two section commutator and a pair of slip-rings on its shaft and is so constructed that the wire cannot slip off the iron core. The upper bearing and brushes for the commutator are mounted on a strong upright. Separate brushes are provided for the commutator and for slip rings and each are connected to a terminal. The magnets are held in position by thumb screws.

Description

Each wound on a rectangular insulated bobbin, connections by 4 mm sockets spaced at 19 mm