Logic Gates

A Project Report On WORKING OF LOGIC GATES SUBMITTED BY:- Shamil Choudhury ROLL__________ No_____________ Karimganj Junior College Of Science CONTENTS†¦Ã¢â‚¬ ¦.. TOPICS Page No 1. CERTIFICATE1 2. INTRODUCTION 2 3. THEORY3-4 4. EXPERIMENT5-6 5. RESULTS 7 6. CONCLUSION. 7 7. ACKNOWLEDGEMENT 8 8. REFERENCE 9 INTRODUCTION A gate is a digital circuit that follows certain logical relationship between the input and output voltages. Therefore, they are generally known as logic gates — gates because they control the flow of information. The five common logic gates used are NOT, AND, OR, NAND, NOR. Each logic gate is indicated by a symbol and its function is defined by a truth table that shows all the possible input logic level combinations with their respective output logic levels. Truth tables help understand the behavior of logic gates. These logic gates can be realized using semiconductor devices. Here we will investigate on the working of first three logic gates i. e. OR, AND, and NOT gate. OBJECTIVE OF THE PROJECT To demonstrate the working of logic gates using torch bulb, battery and switches. APPARATUS REQUIRED To demonstrate the working of the logic gates we require the following apparatus:- i) A BATTERY OF 6 V. ii) TWO SWITCHES (KEYS). iii) TORCH BULB. iv) CONNECTING WIRES THEORY There are three basic logic gates: 1. The OR Gate * An OR gate has two or more inputs with one output. It operates in such a way that a output is high (i. e. 1) if one of the two inputs (or both the inputs) is high. The symbol of OR Gate is It works on the following truth table:- 2. The AND GATE * An AND gate has two or more inputs and one output. It operates in such a way that the output is high (i. . 1) when both the inputs are high. The symbol of AND Gate is It works on the following truth table:- 3. The NOT Gate * The NOT gate has single input and single output. The output is not the same as input. If the input is low (i. e. 0), the output is high (i. e. 1). On the other hand, the output will be low (i. e. 0) if the input is high (i. e. 1). In other words it performs a negation operation on the input and call ed the invertor. The symbol of NOT Gate is It works on the following truth table:- PROCEDURE (1) Working of OR Gate The electric circuit diagram is as shown Using the above circuit diagram we proceed as follows: (i) The switches S1 and S2 are not pluged and the glow of the bulb is recorded (do not glow) . (ii) Now the switch S1 is plugged (not S2), it is found that the bulb glows. (iii) Now the switch S2 is plugged (not S1), it is observed that the bulb glows. (iv) Both the switches are plugged, the bulb glows. (2) Working of AND gate The electric circuit diagram is shown Using the above circuit diagram we proceed as follows: (i) The switches S1 and S2 are not plugged and the glow of the bulb is recorded (do not glow) . ii) Now the switch S1 is plugged (not S2), it is found that the bulb does not glow. (iii) Now the switch S2 is plugged (not S1), it is observed that the bulb does not glow. (iv) Both the switches are plugged, the bulb glows. 3. Working of NOT gate The electric circuit diagram is shown Using the above circuit diagram we proceed as follows: (i) The switch S is not plugged and the glow of the bulb is recorded(the bulb glows) . (ii) The switch S is plugged and the glow of the bulb is recorded(the Bulb does not glow). RESULT 1. Results for the OR gate S1 | S2| Bulb glows| Off On Off On| Off Off On On| No Yes Yes Yes| 2. Results for the AND gate S1 | S2| Bulb glows| Off On Off On| Off Off On On| No No No Yes| 3. Results for the NOT gate S| Bulb glows | Off On| Yes No| CONCLUSION Thus we find that the logic gates works according to their corresponding truth table. ACKNOWLEDGEMENT I extend my sincere thanks to our Dr Sujit Tiwari for his advice and help in the matter of preparing the project. I also express my deep sense of gratitude to my friends forextending all possible help in supplying project information, which I have used while preparing the project. They have given lots of information for preparation of the report I sought. My parents have supplied me all kinds of necessary materials and information for the report files. Hence, I am grateful to them also. REFERENCE [1] Concept of Physics – H. C. Verma. [2] Comprehensive Practical Physics.