Logic Gates Essentials Quiz Quiz

Challenge your understanding of logic gates in digital electronics with practical scenarios and technical concepts. This quiz covers gate functions, truth tables, circuit applications, and key terminology for students and enthusiasts in electronics communication.

1. Basic Logic Gate Identification

   Which logic gate outputs HIGH only when both of its inputs are HIGH, such as when A = 1 and B = 1?

   1. AND gate
   2. OR gate
   3. NAND gate
   4. XOR gate

   Explanation: The AND gate produces a HIGH output only when all its inputs are HIGH, making it the correct answer for this scenario. An OR gate outputs HIGH if at least one input is HIGH, which is less restrictive. A NAND gate is the opposite of AND, outputting LOW when both inputs are HIGH. The XOR gate outputs HIGH when only one input is HIGH, not when both are HIGH. Thus, only the AND gate fits the given condition.

2. Gate Symbol Recognition

   If you see a diagram with a curved input and a small bubble at the output, which logic gate does it most likely represent?

   1. NOR gate
   2. AND gate
   3. XAND gate
   4. OR gate

   Explanation: A NOR gate symbol features an OR gate's curved input and a small circle (bubble) at the output, representing inversion. The AND gate uses a straight-edged symbol without a curved input or output bubble. XAND is not a standard logic gate, making it incorrect. OR gate lacks the output bubble, representing non-inverting behavior. Thus, NOR gate is the only one matching the diagram description.

3. Truth Table Logic

   In a NOT gate, what will be the output if the input is logic LOW (0)?

   1. HIGH (1)
   2. LOW (0)
   3. Undefined
   4. Two outputs

   Explanation: A NOT gate inverts the input, so a logic LOW (0) becomes HIGH (1) at the output. Selecting LOW (0) would ignore the inverting function of this gate. 'Undefined' is incorrect because the output is always well-defined for digital logic gates. 'Two outputs' is incorrect since a standard NOT gate has only one output. The correct behavior is HIGH (1).

4. Application Scenario

   Which logic gate would you use to produce an output HIGH only if exactly one of two inputs is HIGH, such as in an odd parity checker?

   1. XOR gate
   2. NAND gate
   3. AND gate
   4. XNOR gate

   Explanation: An XOR gate outputs HIGH if and only if the number of HIGH inputs is odd, which makes it suitable for odd parity checking. A NAND gate does not implement this exclusive-or behavior and serves a different function. The AND gate would require both inputs to be HIGH. The XNOR gate outputs HIGH for an even number of HIGH inputs, which is the opposite of what is required. Hence, the XOR gate is the proper choice.

5. Combinational Logic

   A circuit combines a NAND gate followed by a NOT gate (inverter). What is the overall logic function of this combination?

   1. AND gate
   2. OR gate
   3. NAND gate
   4. NOR gate

   Explanation: Placing a NOT gate (inverter) after a NAND gate inverts the output, making the overall function identical to an AND gate. An OR gate's behavior is unrelated to this combination. If the inverter was not included, it would just be a NAND gate, and not NOR, as NOR is an OR gate with inversion, not NAND. Thus, the correct answer is AND gate.