Saturday, 28 May 2011
The propagation of a linearly polarized electromagnetic wave: the vectors of the electric field E and the magnetic field H are perpendicular to each other and to the direction of the wave propagation. In the running wave the vectors E and H oscillate in phase, i.e. they achieve the maximum value in the same points of the space.
Arvind Electrical: working of solar panel
Arvind Electrical: working of solar panel: "Most of people don't think much about where our electricity comes from, only that it's available and plentiful. Electricity generated by bu..."
Friday, 27 May 2011
Thursday, 26 May 2011
Wednesday, 25 May 2011
Tuesday, 24 May 2011
Relay
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays were used extensively in telephone exchanges and early computers to perform logical operations.
A type of relay that can handle the high power required to directly control an electric motor is called a contactor. Solid-state relays control power circuits with nomoving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays".
Monday, 23 May 2011
Saturday, 21 May 2011
Friday, 20 May 2011
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