1. ELECTRICITY & MAGNETISM BY: Arana Rampersad Form: 5D Physics

2. ELECTRONICS RECTIFICATION

3. RECTIFICATION What is Rectification? What is Rectification? Rectification is the process of converting alternating current (a.c.) to direct current (d.c.). This is done by a device called a rectifier. A device which performs the opposite function (converting DC to AC) is known as an inverter. A device which performs the opposite function (converting DC to AC) is known as an inverter.

4. RECTIFICATION FULL WAVE RECTIFICATION FULL WAVE RECTIFICATION A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the input waveform to DC (direct current), and is more efficient.

5. RECTIFICATION HALF WAVE RECTIFICATION HALF WAVE RECTIFICATION In half wave rectification, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, it is very inefficient if used for power transfer. In half wave rectification, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, it is very inefficient if used for power transfer.

6. How can a semiconductor diode be used in half wave rectification The two types of semiconductors are: p-type (doped with group 3 elements) and n-type (doped with group 5 elements.) The two types of semiconductors are: p-type (doped with group 3 elements) and n-type (doped with group 5 elements.) A diode is used for rectifying an alternating current, i.e., to obtain from it current which flows in one direction only. A diode is used for rectifying an alternating current, i.e., to obtain from it current which flows in one direction only. An alternating voltage is applied to the anode by connecting it to one end of the secondary of a mains transformer, which may be either step-up or step-down according to the voltage required. The cathode heater coil is supplied with current from a separate low-voltage required. The cathode heater coil is supplied with current from a low-voltage secondary winding on the same transformer. The unidirectional current output is obtained from connections made to the other end of the secondary and the cathode respectively. An alternating voltage is applied to the anode by connecting it to one end of the secondary of a mains transformer, which may be either step-up or step-down according to the voltage required. The cathode heater coil is supplied with current from a separate low-voltage required. The cathode heater coil is supplied with current from a low-voltage secondary winding on the same transformer. The unidirectional current output is obtained from connections made to the other end of the secondary and the cathode respectively.

7. How can a semiconductor diode be used in half wave rectification The action is that during that half of the cycle when the anode is positive it attracts electrons from the space charge, and hence a current flows in the anode circuit. During the other half of the cycle, when the anode becomes negative, it repels electrons, and consequently no current flows. The output therefore consists of a series of impulses or half waves in the same direction. The action is that during that half of the cycle when the anode is positive it attracts electrons from the space charge, and hence a current flows in the anode circuit. During the other half of the cycle, when the anode becomes negative, it repels electrons, and consequently no current flows. The output therefore consists of a series of impulses or half waves in the same direction.

8. Differentiate between direct current from batteries and rectified alternating current by a consideration of the V-t graphs for both cases. Rectifying Alternating Current (AC) Rectifying Alternating Current (AC) Alternating Current (AC) flows one way, then the other way, continually reversing direction. An AC voltage is continually changing between positive (+) and negative (-). Alternating Current (AC) flows one way, then the other way, continually reversing direction. An AC voltage is continually changing between positive (+) and negative (-). The rate of changing direction is called the frequency of the AC and it is measured in hertz (Hz) which is the number of forwards-backwards cycles per second. The rate of changing direction is called the frequency of the AC and it is measured in hertz (Hz) which is the number of forwards-backwards cycles per second.

9. Differentiate between direct current from batteries and rectified alternating current by a consideration of the V-t graphs for both cases. Rectifying Alternating Current (AC) Rectifying Alternating Current (AC) The diagram below shows a.c. from power supply. The shape is called a sine wave.

10. Differentiate between direct current from batteries and rectified alternating current by a consideration of the V-t graphs for both cases. Direct Current (DC) from batteries. Direct Current (DC) from batteries. Direct Current always flows in the same direction, but it may increase and decrease. A DC voltage is always positive (or always negative), but it may increase and decrease. Direct Current always flows in the same direction, but it may increase and decrease. A DC voltage is always positive (or always negative), but it may increase and decrease. Electronic circuits normally require a steady DC supply which is constant at one value or a smooth DC supply which has a small variation called ripple. Electronic circuits normally require a steady DC supply which is constant at one value or a smooth DC supply which has a small variation called ripple. Cells, batteries and regulated power supplies provide steady DC which is ideal for electronic circuits. Cells, batteries and regulated power supplies provide steady DC which is ideal for electronic circuits.

11. Differentiate between direct current from batteries and rectified alternating current by a consideration of the V-t graphs for both cases. Direct Current (DC) from batteries. Direct Current (DC) from batteries. The diagram below show steady d.c. from a battery.

12. A simple test to determine whether a semiconductor diode is defective. A diode is like a one-way electronic valve. Electrons flow only one way through a diode junction. When a source of more positive potential is applied to the anode, the diode will conduct. This is what is called "forward biasing". If the diode is reversed, current will not pass through the diode. This is what is called "reverse biasing". The circuit shown below shows the tester light illuminate. A diode is like a one-way electronic valve. Electrons flow only one way through a diode junction. When a source of more positive potential is applied to the anode, the diode will conduct. This is what is called "forward biasing". If the diode is reversed, current will not pass through the diode. This is what is called "reverse biasing". The circuit shown below shows the tester light illuminate.

13. A simple test to determine whether a semiconductor diode is defective. The picture shows the tester illuminating with a diode forward biased. The cathode (banded end) of the diode is in the alligator clip. If you shorten the alligator clip to the probe tip you will see a brighter illumination than when connected to the diode. This is called a voltage drop across the diode junction. If you reverse the diode, the tester will not light. This is a good diode. The picture shows the tester illuminating with a diode forward biased. The cathode (banded end) of the diode is in the alligator clip. If you shorten the alligator clip to the probe tip you will see a brighter illumination than when connected to the diode. This is called a voltage drop across the diode junction. If you reverse the diode, the tester will not light. This is a good diode. If the light illuminates brightly both ways, or neither way, the diode is defective. Note that it must light only in one direction. If the light illuminates very dimly on only one direction and not the other, the diode may still be okay. If the light illuminates brightly both ways, or neither way, the diode is defective. Note that it must light only in one direction. If the light illuminates very dimly on only one direction and not the other, the diode may still be okay.

14. ELECTRONICS LOGIC GATES

15. Logic gates are the fundamental components in digital electronics. Logic gates are the fundamental components in digital electronics. There are five basic logic gates: NOT, AND, OR, NAND and NOR. There are five basic logic gates: NOT, AND, OR, NAND and NOR. A useful tool which analyses the inputs and outputs of one or more gates by logging them in an orderly manner is known as a truth table. A useful tool which analyses the inputs and outputs of one or more gates by logging them in an orderly manner is known as a truth table.

16. Symbols for NOT, AND, OR, NAND and NOR logic gates. NOT GATE OR INVERTER NOT GATE OR INVERTER A is the input and B is the output.

17. Symbols for NOT, AND, OR, NAND and NOR logic gates. AND GATE AND GATE A and B are the inputs and C is the Output.

18. Symbols for NOT, AND, OR, NAND and NOR logic gates. OR GATE OR GATE A and B are the inputs and C is the Output.

19. Symbols for NOT, AND, OR, NAND and NOR logic gates. NAND GATE NAND GATE A and B are the inputs and C is the Output.

20. Symbols for NOT, AND, OR, NAND and NOR logic gates. NOR GATE NOR GATE A and B are the inputs and C is the Output.

21. The Functions of each gate with the aid of truth tables. NOT GATE OR INVERTER NOT GATE OR INVERTER This gate has one input and one output. The output of a not gate is the inverse of the input. For example, if the input is high or 1 the output is low or 0. This gate has one input and one output. The output of a not gate is the inverse of the input. For example, if the input is high or 1 the output is low or 0. Truth Table Truth Table INPUTOUTPUT 01 10

22. The Functions of each gate with the aid of truth tables. AND GATE AND GATE This gate has two or more inputs and one output. The output is high or on only if all the inputs are high or on. Under any other conditions the output is low or off. This gate has two or more inputs and one output. The output is high or on only if all the inputs are high or on. Under any other conditions the output is low or off. Truth Table Truth Table INPUT AINPUT BOUTPUT 000 010 100 111

23. The Functions of each gate with the aid of truth tables. OR GATE OR GATE This gate has two or more inputs and one output. The output is high or on as long as one or more of the inputs are high or on. Under any other conditions the output is low or off. This gate has two or more inputs and one output. The output is high or on as long as one or more of the inputs are high or on. Under any other conditions the output is low or off. Truth Table Truth Table INPUT AINPUT BOUTPUT 000 011 101 111

24. The Functions of each gate with the aid of truth tables. NAND GATE NAND GATE This gate has two or more inputs and one output. The output is low or off only if all the inputs are high or on. Under any other conditions the output is high or on. This gate has two or more inputs and one output. The output is low or off only if all the inputs are high or on. Under any other conditions the output is high or on. Truth Table Truth Table INPUT AINPUT BOUTPUT 001 011 101 110

25. The Functions of each gate with the aid of truth tables. NOR GATE NOR GATE This gate has two or more inputs and one output. The output is high or on only if all the inputs are low or off. Under any other conditions the output is low or off. This gate has two or more inputs and one output. The output is high or on only if all the inputs are low or off. Under any other conditions the output is low or off. Truth Table Truth Table INPUT AINPUT BOUTPUT 001 010 100 110

26. Circuits involving the combinations of no more than three logic gates. Constructing a NOT gate using NAND gates. Constructing a NOT gate using NAND gates. Constructing a OR gate using NAND gates. Constructing a OR gate using NAND gates.

27. Circuits involving the combinations of no more than three logic gates. Constructing a AND gate using NAND gates. Constructing a AND gate using NAND gates. Constructing a NOT gate using NOR gates. Constructing a NOT gate using NOR gates.

28. Circuits involving the combinations of no more than three logic gates. Constructing a OR gate using NOR gates. Constructing a OR gate using NOR gates. Constructing a AND gate using NOR gates. Constructing a AND gate using NOR gates.