Electrics Essay Example | Topics and Well Written Essays - 2250 words

Electrics - Essay Example one watt is equivalent to 1 joule of energy per second. It is basically a measure of the rate of energy consumption. All the electrical appliances like bulb, refrigerator, television sets, computer, printer, iron consume some amount of electricity which decides their wattage. As a thumb rule, more the wattage more will be electrical consumption by that product. v. Farad (F): It is the SI unit of capacitive charge. An electric capacitor is made up of two parallel plates. As a result of electrical current some charge is stored on the plates of the capacitor. This charge is measured in Farad. One Farad is the capacitance having an equal and opposite charge of 1 coulomb on each plate and a voltage difference of 1 voltage between the plates. If the charge stored is less in quantity, it is measured in Micro-Farad (F) or Pico-Farad (pF). vi. Henry (H): It is the measure of inductive force produced in an inductor. Electromotive force is produced when we vary the current in an inductor. One volt of electromotive force (emf) is produced when the current is varied at the rate of one ampere per second. The unit is named after Joseph Henry, an American scientist of 18th century, who discovered electromagnetic induction. a. Temperature Coefficient of Resistance: This coefficient depicts the effect of temperature on the resistance of an electrical conductor. Increase or decrease of temperature affects the movement of the molecules within an atom. As temperature rises the movement increases, which in turn results in more collision amongst the molecules, thus impacting the specific resistance of the material. Therefore, in general the value of resistance (measured in ohms) of a material will depend upon the temperature coefficient of the resistance for the conductor. The total resistance for a material can be defined as; R = Rref [1 + (T-Tref)] Ohms or Where, R = Resistance of the conductor at a temperature, 'T' Rref = Resistance of conductor at a reference temperature of Tref. The Tref is usually 200C and sometimes for experimental purposes it is 00C. = Temperature coefficient of resistance for conductor material. T = Conductor temperature in degrees Celsius T = Reference temperature at which the Temp. Coefficient for the material is defined b. Relative Permittivity of Substance (r): It is the Ratio of the electric field strength in vacuum to that in a given medium. i.e. r = / o Where is the permittivity of the substance and o is the permittivity of the free space. The relative permittivity is also known as the dielectric strength of the substance. The dielectric constant is a complex constant with the real part giving reflective surface properties. The relative permittivity values affect the magnetic and electric behaviour of a conductor. The value of relative permittivity of a given substance keeps varying depending upon the electrical frequency, temperature etc. c. Magnetic Hysteresis: The Hysteresis is a magnetic property of a substance. This phenomenon is generally observed in ferromagnetic substances like Iron, nickel, cobalt etc. This group is called ferromagnetic as iron or 'ferric' is an