1.
Suppose inverters are placed in series with both inputs of an AND gate. Under whatconditions is the output of the resulting black box high?
Correct Answer
B. If and only if both inverter inputs are low
Explanation
The output of the resulting black box is high if and only if both inverter inputs are low. This means that both inverters are in the "off" state, which results in a high output for the AND gate. If either or both of the inverter inputs are high, the output will be low. Therefore, the only condition for a high output is when both inverter inputs are low.
2.
Suppose an AND gate is followed by an inverter. Under what conditions is the output of theresulting black box low?
Correct Answer
A. If and only if both inputs are high
Explanation
The output of the resulting black box will be low only when both inputs of the AND gate are high. This is because an AND gate produces a high output only when both of its inputs are high. The inverter then inverts this high output to a low output. Therefore, the output of the black box will be low if and only if both inputs are high.
3.
What is the binary equivalent of decimal 29?
Correct Answer
B. 11101
Explanation
The binary equivalent of decimal 29 is 11101.
4.
In Boolean algebra, addition represents
Correct Answer
C. The logical OR operation.
Explanation
In Boolean algebra, addition represents the logical OR operation. The logical OR operation returns true if at least one of the inputs is true, and false otherwise. This is similar to addition in arithmetic, where the sum is true if at least one of the numbers being added is true. Therefore, addition in Boolean algebra is used to combine logical statements and determine if any of them are true.
5.
If the output to a logical inverter is low, it means that
Correct Answer
C. The single input is high.
Explanation
If the output to a logical inverter is low, it means that the single input is high. In a logical inverter, the output is the opposite of the input. So, if the output is low, it means that the input must be high in order to be inverted to a low output.
6.
What is the decimal equivalent of binary 1111?
Correct Answer
A. 15
Explanation
The binary number 1111 represents the decimal number 15. In binary, each digit represents a power of 2, starting from the rightmost digit as 2^0 and increasing by a power of 2 for each subsequent digit. Therefore, the binary number 1111 can be calculated as 1 * 2^3 + 1 * 2^2 + 1 * 2^1 + 1 * 2^0, which equals 8 + 4 + 2 + 1, resulting in the decimal number 15.
7.
The output of an AND gate is high if and only if
Correct Answer
D. All inputs are high.
Explanation
The output of an AND gate is high if and only if all inputs are high because an AND gate requires all inputs to be high in order to produce a high output. If any of the inputs are low, the output will be low. Therefore, the correct answer is all inputs are high.
8.
DeMorgan’s Theorem states that, for all logical statements X and Y,
Correct Answer
D. (−X)+(−Y) is equivalent to −(X*Y).
Explanation
DeMorgan's Theorem is a fundamental principle in logic. It states that the negation of a conjunction (logical AND) is equivalent to the disjunction (logical OR) of the negations of the individual statements. In this case, the correct answer states that the negation of the sum of two logical statements, (-X) and (-Y), is equivalent to the negation of their conjunction, -(X*Y). This follows the principle of DeMorgan's Theorem, making it the correct answer.
9.
If you see a number represented by FF in the documentation for an electronic circuit orsystem, you can be certain that the number is
Correct Answer
A. Radix 16.
Explanation
The number FF is commonly used to represent the hexadecimal value 255. In hexadecimal, each digit represents 16 raised to a power, ranging from 0 to 15. Since FF represents the maximum value in a two-digit hexadecimal number, it indicates that the number is in radix 16.
10.
Which of the following codes is digital?
Correct Answer
D. All of the above
Explanation
All of the codes mentioned in the options (Morse, Baudot, and ASCII) are digital codes. Morse code is a digital code that uses a combination of dots and dashes to represent letters and numbers. Baudot code is also a digital code that uses a combination of 5-bit sequences to represent characters. ASCII (American Standard Code for Information Interchange) is a widely used digital code that represents characters using 7 or 8 bits. Therefore, all three codes mentioned are examples of digital codes.
11.
Which of the following voltages could normally represent a 1 in positive logic?
Correct Answer
C. +5 V
Explanation
In positive logic, a logic 1 is typically represented by a higher voltage level compared to a logic 0. Among the given options, +5 V is the highest voltage and therefore could normally represent a 1 in positive logic.
12.
Which of the following voltages might normally represent a 1 in negative logic?
Correct Answer
A. 0.0 V
Explanation
In negative logic, a 1 is represented by a low voltage level. Therefore, the voltage that might normally represent a 1 in negative logic is 0.0 V, as it is the lowest voltage level among the given options.
13.
Fill in the blank to make the following sentence true: “ data transmission refers to digitalbits sent along a single line, one bit after another.”
Correct Answer
A. Serial
Explanation
Serial data transmission refers to the process of sending digital bits along a single line, one bit after another. This method of transmission is characterized by the sequential transfer of data, where each bit is transmitted one at a time. It is commonly used in communication systems where the data needs to be sent over long distances or in a continuous stream. In contrast, parallel data transmission involves sending multiple bits simultaneously on separate lines, synchronous transmission refers to the coordination of data transfer with a clock signal, and analog transmission refers to the continuous representation of data.
14.
The inputs of an R-S flip-flop are known as
Correct Answer
D. Reset and set.
Explanation
The inputs of an R-S flip-flop are known as reset and set because these inputs control the state of the flip-flop. The reset input is used to set the flip-flop to a known state, typically a logic 0, while the set input is used to set the flip-flop to a logic 1 state. These inputs allow the flip-flop to be controlled and manipulated based on the desired functionality of the circuit.
15.
When both inputs of an R-S flip-flop are 0,
Correct Answer
A. The outputs stay as they are.
Explanation
When both inputs of an R-S flip-flop are 0, it means that both the Set and Reset inputs are inactive. In this state, the flip-flop retains its previous state, and the outputs stay as they are. This means that the output Q will remain 0, and its complement -Q will remain 1. Therefore, the correct answer is that the outputs stay as they are.
16.
The fifth digit from the right in a binary number carries which decimal value?
Correct Answer
D. 16
Explanation
The fifth digit from the right in a binary number carries the decimal value of 16. In binary representation, each digit represents a power of 2, starting from the rightmost digit as 2^0. Therefore, the fifth digit from the right represents 2^4 which equals 16.
17.
What is the octal equivalent of binary 1010?
Correct Answer
C. 12
Explanation
The octal equivalent of binary 1010 is 12. In octal, each digit represents three binary digits. So, starting from the right, the binary digits 10 can be converted to octal as 1*2^1 + 0*2^0, which equals 2 in decimal. Therefore, the octal equivalent of binary 1010 is 12.
18.
What is the largest possible radix 10 number that can be represented as a six-digit binarynumber?
Correct Answer
D. Decimal 63
Explanation
The largest possible radix 10 number that can be represented as a six-digit binary number is decimal 63. This is because a six-digit binary number can have a maximum value of 111111 in binary, which is equal to 63 in decimal.
19.
If one of the inputs to a two-input NOR gate is high, what is the output state?
Correct Answer
B. Low
Explanation
If one of the inputs to a two-input NOR gate is high, the output state will be low. This is because a NOR gate produces a low output only when both of its inputs are high. Since one of the inputs is already high, the output will be low regardless of the state of the other input.
20.
Suppose a logic circuit has four inputs W, X, Y, and Z. How many possible inputcombinations are there?
Correct Answer
C. 16
Explanation
The number of possible input combinations can be calculated by raising 2 to the power of the number of inputs. In this case, since there are four inputs (W, X, Y, and Z), the number of possible combinations is 2^4 = 16.