# Instrumentation Transducers Questions and Answers – Encoders and Decoders

This set of Instrumentation Transducers Multiple Choice Questions & Answers (MCQs) focuses on “Encoders and Decoders”.

1. A decoder converts n inputs to __________ outputs.
a) n
b) n2
c) 2n
d) nn

Explanation: Decoder is a circuit with n input lines and 2n output lines.

2. Which of the following are building blocks of encoders?
a) NOT gate
b) OR gate
c) AND gate
d) NAND gate

Explanation: Encoders are made up of three OR gates.

3. Which of the following can be represented for decoder?
a) Sequential circuit
b) Combinational circuit
c) Logical circuit
d) None of the mentioned

Explanation: Combinational circuit in which output depends only on the state of inputs.

4. BCD to seven segment conversion is a ________________
a) Decoding process
b) Encoding process
c) Comparing process
d) None of the mentioned

Explanation: BCD to seven segment code conversion can be treated as a decoding process.

5. Which of the following is a decoder IC?
a) 7890
b) 8870
c) 4047
d) 4041

Explanation: 8870 is a DTMF decoder circuit, which decodes DTMF tune and produces corresponding output.
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6. DTMF stands for ________________
a) Dual Tone Magnetic Frequency
b) Double Tone Magnetic Frequency
c) Dual Tone Multiple Frequency
d) Dual Tone Mechanical Frequency

Explanation: DTMF is the short form of Dual Tone Multiple Frequency.

7. Invalid BCD can be made to valid BCD by adding with _______________
a) 0101
b) 0110
c) 0111
d) 1001

Explanation: Invalid BCD are numbers greater than 1001, and they can be made valid BCD by adding with 0110.

8. Decoder is constructed from ________________
a) Inverters
b) AND gates
c) Inverters and AND gates
d) None of the mentioned

Explanation: Decoder circuits are constructed from Inverters and AND gates.

9. Which of the following represents a number of output lines for a decoder with 4 input lines?
a) 15
b) 16
c) 17
d) 18

Explanation: For n input lined decoder will have 2n output lines.

10. Decoders and Encoders are doing reverse operation.
a) True
b) False

Explanation: Encoders encode the data to a binary number and decoders decode the original data from binary codes.

Sanfoundry Global Education & Learning Series – Instrumentation Transducers.

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