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Explain the following terms:- Tree :- it is a inter-connected open set of branches which include all the nodes at a given graph without forming any closed path.  Co- Tree :- From the oriented graph, if a tree is removed, the resultant is known as co tree or complement of tree.  Link :- It is a branch of a graph which does not belong to the particular tree, known as link . The link are present in the tree.  Graph :- The graph is also called as the collection of different points called as the node and different lines called as elements. These buses are interconnected through elements.  Nodes :- A point where two or more circuit elements branches meet is called a node.  Loop : - loop is a closed path of a circuit but all match are loops and the loop is not necessarily a mesh. 

Calculate the pic rating of the diode used in the full wave rectifier shown as . Also find the maximum DC voltage that can be obtained from the circuit. mark the polarity on the millimetre.  Solution :- Number of turns in primary binding Np = 1000 Number of turns in secondary binding Ns = 50 Vp = 220 V Np/Ns = Vp/Vs 1000/50= 220/Vs Vs = 11v Vrms = Vm/√2  => Vm = Vrms √2 => Vm = 11 √2 Vm = 15.5563 v Vdc = 2Vm /π Vdc = 15.5563/π = 9.90V I = V/R => 9.90/1×1000 I = 9.9mA PIV  = 2Vm = 2 × 15.5563   PIV= 31.112 V

Calculate the maximum DC voltage available from a half wave rectifier Shown . Also find the reading of the milli ammeter.  Solution:- Turn ratio of transformer = 20:1 Number of turns in primary binding = 20 Number of turns in secondary binding = 1 Mains voltage supply(1/p) Vp = 220 v From the Transformer ratio formula Np/Ns = Vp/Vs 20/1 = 220/ Vs Vs = 220/20 = 11V Vrms = Vm/√2  => Vm = Vrms √2 => Vm = 11 √2 Vm = 15.5563 v Vdc =  2Vm /π Vdc = 2×15.5563/π = 9.90V I = V/R => 9.90/1×1000 I = 9.90mA

What do you mean by zener diode, explain its working principle with neat and clean diagram?  Zener diode is a special type of diode designed to reliably allow current to flow "backward" (that is Reverse Biased) when a certain set reverse voltage known as a zener voltage is reached. zener diode are manufactured with a great variety of Zener voltage and some even variable.  Working principle:- When a PN junction diode is highly doped ,  then concentration of impurity atoms will be high in the Crystal. The higher concentration of impurity atoms cause the highest concentration of ions in the depletion layer. Hence for some applied reverse Bias Voltage the width of depletion layer , becomes than that  in a normally doped diode due to thinner depletion layer, voltage gradient for electric field strength across the depletion layer is quite high. if the reverse voltage is continued to increase, after a certain applied voltage , the electron from the covalent bonds  within the depleti

What do you mean by bleeder resistor?  Bleeder Resistor is a resistor connected in a parallel with the output of a High Voltage power supply circuit for the purpose of discharging the electric charge stored in the power supply is filter capacitor when the equipment is turned off , for safety reasons. 

Explain the following: (I) PN junction diode in forward bias:- When a diode is connected in a forward bias condition a negative voltage is applied to the n type material and a positive voltage is applied to the P type material. If the external voltage becomes greater than the value of potential barrier which is 0.7 volt for Silicon and 0.3 for Germanium then current will start to flow.  (II) Zener effect:- Zener Effect /diode is a type of electrical breakdown. it occurs in the reverse bias PN junction diode when the electric field enables tunneling of the electron from the valence to the conduction band of a semiconductor, leading to numerous free minority carrier which suddenly increased the reverse current.  (iii)   Avalanche effect : - It is a sudden rapid increase in the current when a sufficient amount of electrical force is applied to the semiconductor material.  (iv) Reverse saturation current :- It is a kind of leakage current or invented current flows when Semiconductor device

Write a short note on formation of depletion region.  A PN junction is formed using a positive and negative semiconductor.  When the two semiconductor are joined together , the electron from the n-side are diffused to the n- reason and they form a layer of negative charges from the pyside are diffuse to the end the season and they form a layer of positive charge on the n - side . The reason between those two layer is the depletion region of the semiconductor.