To construct a full wave rectifier and show that that Alternating Current is rectified into a Direct Current.
Introduction A full wave rectifier is a device which is used to rectify all the alternating current components in an alternating supply and make it purely a direct current. The two alternating halves of an alternation current are rectified in a full wave rectifier which is an advantage over a half wave rectifier. Most electronic devices cannot withstand very high voltage or alternating current due to its intense high power. The use of batteries in all devices is not practical as their replacement and durability is a huge problem as the device has to be dismantled each time for such a replacement. So these rectifiers are used in most of the electronic devices like TV’s, Radios, Chargers, and Lightings etc.
Materials required in the construction Connecting wires A Plug Single lead wire - 2m 3 Nuts & Bolts 2 to 3cm length A Circuit board A Transformer A Capacitor A Resistor (1 K Ω) P-N junction diodes An LED Insulation tape, Blades, soldering wax, soldering lead, soldering iron & sand paper.
Connection details Connections are done as in the circuit. The A.C. supply is given to both the input wires of the transformer and the two ends of the secondary coil is given to the P side of the two diodes and the N side of the diodes are twined and then connected to one en d of the capacitor and the other end to the centre tap lead and to the resistor. Further, the other end of capacitor with the diode connect ion is connected to the other end of the resistor. Connect 2 leads on both the ends of the resistor to measure the output
and this is connected to the +ve & -ve terminals of the bulb.
1st when the A.C. is supplied to the transformer, it steps down the 230V main supply to 6 volts. It has a capability of delivering a current of 500mA. The 6 volts A.C. appearing across the secondary is the RMS value and the peak value is 8.4 volts. During the 1st half cycle of the A.C. input Diode D1 is forward biased and a current ‘I’ flows in the circuit in the direction S1D1 ABEOS1. During this time diode D2 is reverse biased. So it does not conduct any electric current. During the next half cycle the diodeD2 is forward and D1 is reversed. Hence D2 conducts current in the direction S2D2ABEOS2 and D1 does not conduct any current. In subsequent half cycles of the A.C current the above processes are repeated. In both the half cycles it is clear that current flows through the resistor in only one direction ABE. Even though the voltage across RL is unidirectional it will still contain a few A.C components. This is filtered and made smooth using a capacitor, which filters 99% of the A.C current. A resistor is then used to adjust the output voltage. Capacitor also nearly filters all A.C components from the supply and resistance is adjusted for the required output. As this is a simple circuit, only one capacitor and a resistance are being used. But there will be slight factor of A.C. current still left in the output but it
is negligible. The output Direct Current and voltage light up the LED.
BIBLIOGRAPHY Physics-Textbook for Class XII ; NCERT Modern’s abc of PHYSICS Encyclopaedias
ACKNOWLEDGEMENT I would like to express my sincere gratitude to my physics mentor Mr Anish Pillai, for his vital support, guidance and encouragement throughout the year. I am grateful to my parents whose blessings and wishes have gone a long way in the completion of this arduous task. I thank my friends and batch mates, without their prompt support my efforts would have been in vain. THANK YOU ALL!!
Daksh Patel XII-B
This is to certify that Mr Daksh Patel of class XII of Bharatiya Vidya Bhavans has successfully completed the project on “FULL WAVE RECTIFIER” within the stipulated time with sincerity and devotion under my guidance towards the fulfilment of credit for the Physics Project evaluation.