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Dc motor

Dc motor

In any electric motor, operation is based on simple electromagnetism. A current-carrying conductor generates a magnetic field; when this is then placed in an external magnetic field, it will experience a force proportional to the current in the conductor, and to the strength of the external magnetic field. As you are well aware of from playing with magnets as a kid, opposite (North and South) polarities attract, while like polarities (North and North, South and South) repel. The internal configuration of a DC motor is designed to harness the magnetic interaction between a current-carrying conductor and an external magnetic field to generate rotational motion.

Who invented the circuit breaker?

Who invented the circuit breaker?

Thomas Edison developed the idea for a circuit breaker in 1879, sketched different concepts in his scientific journals and patented the idea the same year. A circuit breaker disconnects an electrical circuitry by opening a contact when the circulating electrical current reaches levels considered unsafe for the system. Circuit breakers equip every electrical system today, more than 120 years after being invented.

Circuit braker

Introduction of circuit breakers

All electric circuits needs a switching device and also a protective device. Switchgear is the general term covering a wide range of equipment connected with switching and protection. A circuit breaker is a switching and circuit interrupting device. A circuit breaker serves two purposes:

 Switching on and off during normal operation for maintenance etc.

 Switching during abnormal conditions- short circuits, earthing etc. to protect the associated equipment.

In short, a circuit breaker is a sort of automatic switch which can interrupt the fault currents. Two important parts of a circuit breaker that need consideration are:

Arc extinction system

Relay for operation

Electrical engineers: First solar car

Electrical engineers: First solar car: First solar car: The first solar car invented was a tiny 15-inch vehicle created by William G. Cobb of General Motors. Called the Sunmo...

First solar car

First solar car:

The first solar car invented was a tiny 15-inch vehicle created by William G. Cobb of General Motors. Called the Sunmobile, Cobb showcased the first solar car at the Chicago Powerama convention on August 31, 1955. The solar car was made up 12 selenium photovoltaic cells and a small Pooley electric motor turning a pulley which in turn rotated the rear wheel shaft. The first solar car in history was obviously too small to drive.

Now, let's jump to 1962 when the first solar car that a person could drive was demonstrated to the public. The International Rectifier Company converted a vintage model 1912 Baker electric car (pictured above) to run on photovoltaic energy in 1958, but they didn't show it until 4 years later. Around 10,640 individual solar cells were mounted to the rooftop of the Baker to help propel it.

Incandescent lamp

1. How it Works

Incandescent bulbs work by sending electric current through a resistive material. Typically materials will glow before reaching a melting point. Most materials will glow a dull red color when they reach around 525 Celsius. Most materials will catch fire or melt and can not make a good filament.

Filaments are made from materials that have a high melting point. Tungsten can reach up to 3422 C before it melts. This is a higher temperature than any lamp will reach (except the carbon arc lamp which gets to 3500 C). Other materials have made good filaments or parts of filaments including tantalum, molybdenum, and carbon.

Why does the material emit light when you pass electrical current through it?

When you pass current through a filament material, the resistance creates heat. Atoms in the material absorb energy. Electrons around the atoms are excited and temporarily reach an orbital which is further from the nucleus. When the electron orbit collapses to a lower orbital it ejects the extra energy in the form of a photon.

Incandescence is thermal radiation. Heat is constantly emitted from objects around us, we just can't see it. When heat gets intense enough it reaches wavelengths that we can see. It starts with red and goes up the spectrum. The wavelength/color of the light is a matter of how much energy is being released and what kind of atom is doing the release. In an incandescent bulb most of the heat energy (90%) is emitted in the infrared spectrum which is just below visible light. This is also what makes the lamp inefficient. We don't use that part of the spectrum for the lamp's purpose, we only need the visible spectrum. This is a basic explanation.