# —Resistor are generally made up of semiconductive materials,those are

—Resistor : It is a two-pin device which offers resistance to the electrical circuit which causes a voltage drop across the points between which the resistor is applied.The resistance of a material for a certain shape is given by the relation :-R = (rho * L)/Arho = Resitivity of the material(ohm meter).L = Length of the resistance(in meter).A = Area of cross-section(in meter^2).The resistivity of a material is dependent on the material(which determines the number of charge carriers present in it) and it’s temperature.With increase in it’s temperature the kinetic energy of the charge carrier’s increase which causes an increase in the number of collions the charge carrier undergoes hence causing a increase in the resistance of the material.The resistance offered by any resistor in a given electrical can be cal is given by the relation :-//ImageR = V/I.Where,R = Resistance in ohm’s(S.I unit).V = Potential difference between the points across which the resistor is applied.         I = The Current flowing or passing in the circuit.There exists an inverse relation between the current in the circuit and its resistance,that is with increase in the resistance of the circuit the current decreases and the current in the circuit increases with decrease in resistance of our circuit.A resistor on passing current through it undergoes a heating effect.The heat generated by the resistor on passing the current through it is given byH = (V^2)/R = I^2*R = (V*I)/R whereH = Heat emitted by the resistor(in joules).R = Resistance in ohm’s(S.I unit).V = Potential difference between the points across which the resistor is applied.         I = The Current flowing or passing in the circuit.                                     There primary goal is to a cause a voltage drop in order to prevent overflow of current through the appliances which are being used in our circuit so they don’t operate beyond there power rating and get damaged by excessive heating,due to this excessive heating the resistor may burn and  may lead to the destruction of its components.  Resistors are generally made up of semiconductive materials,those are the materials having electrical conductivity nither too high or too low.The materials used to construct a resistor consist of carbon,metal oxide,etc.Theses materials have chosen because of the following reason :-1)A small number of eletric charge carriers(i.e electrons) due to which the electrical conductance.2)High thermal resistance. // just confirm.—Capacitor :- The capacitor is a device which is used to store electric charge. —LED :- The Light Emitting Diode is a special type of semiconductor device which releases electromagnetic radiation,these elecromagnetic radiation may or may not lie in the visible spectrum on passing current through the LED.The working principle of the Light emitting diode is based upon the quantum theory,according to which when an electron transitions from the higher energy level to an lower energy level then,the energy is emitted by the electron in the form of photons.The energy of the photon released is equivalent to the energy gap between the higher energy level and the lower and energy level of the electron.Only when P-N junction is in the forward biased,only then will the  current move through the diode.The LED is always joined with a resistor in order to prevent any damage to the LED due to extremely large current through it.If no resistor is apllied along with LED the P-N junction will get destroyed ,hence no emission of electromagnetic radiation will take place.     R = (VS-VLED)/ILEDwhere,VS is the source voltage(in volts),VLED is the voltage drop across the LED(in volts),ILED is the current flowing through the LED (in Amperes)  andR is the resistance(in Ohms).