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Block Diagrams & Signal Flow Graphs MCQs for Electrical Engineering (EE) Exam
It covers all Important Questions with answers on Block Diagrams & Signal Flow Graphs for the Electrical Engineering (EE) exam. The questions are based on important topics. Details about the questions:- Topic: Block Diagrams & Signal Flow Graphs
- Type of Questions: MCQs with solutions
- Number of Questions: 35
- You can attempt them on EduRev to score high in Electrical Engineering (EE) exam.
The transfer function C(s)/R(s) for the system described by the block diagram shown below is given by:
- a)
- b)
- c)
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
The transfer function C(s)/R(s) for the system described by the block diagram shown below is given by:
a)
b)
c)
d)
None of these
 | Rhea Reddy answered |
On shifting the take-off point beyond block G, we have the reduced block diagram as shown below:
On further reducing the above block diagram, we get the block diagram as shown below.
On further reducing the above block diagram, we get the block diagram as shown below.
A node having only outgoing branches.- a)Input node
- b)Output node
- c)Incoming node
- d)Outgoing node
Correct answer is option 'A'. Can you explain this answer?
A node having only outgoing branches.
a)
Input node
b)
Output node
c)
Incoming node
d)
Outgoing node
 | Sahil Datta answered |
Answer:
In the context of a node in a graph, an input node refers to a node that has only incoming branches, while an output node refers to a node that has only outgoing branches.
Graph Theory:
Graph theory is a branch of mathematics that deals with the study of graphs, which are mathematical structures used to represent relationships between objects. In a graph, nodes represent objects, and edges represent relationships between those objects.
Nodes and Branches:
In a graph, a node is a point that represents an object, while a branch refers to a connection or link between nodes. Each node can have multiple branches, which connect it to other nodes in the graph. The direction of a branch can be either incoming or outgoing, depending on whether it leads to or originates from a particular node.
Input Node:
An input node, also known as a source node or a root node, is a node in a graph that has only incoming branches. In other words, it is a node that does not have any branches leading outwards. It is called an input node because it is often considered as the starting point or the source of information in a graph.
Output Node:
On the other hand, an output node, also known as a sink node or a leaf node, is a node in a graph that has only outgoing branches. It is a node that does not have any branches leading inwards but only leads to other nodes. It is called an output node because it is often considered as the end point or the destination of information in a graph.
Example:
For example, let's consider a simple graph where nodes A, B, C, and D are connected through branches. If node A has branches leading to nodes B, C, and D, while nodes B, C, and D have branches leading to other nodes but not back to node A, then node A is an input node, and nodes B, C, and D are output nodes.
In this case, the correct answer is option 'A' because an input node is the term used to describe a node that has only incoming branches.
In the context of a node in a graph, an input node refers to a node that has only incoming branches, while an output node refers to a node that has only outgoing branches.
Graph Theory:
Graph theory is a branch of mathematics that deals with the study of graphs, which are mathematical structures used to represent relationships between objects. In a graph, nodes represent objects, and edges represent relationships between those objects.
Nodes and Branches:
In a graph, a node is a point that represents an object, while a branch refers to a connection or link between nodes. Each node can have multiple branches, which connect it to other nodes in the graph. The direction of a branch can be either incoming or outgoing, depending on whether it leads to or originates from a particular node.
Input Node:
An input node, also known as a source node or a root node, is a node in a graph that has only incoming branches. In other words, it is a node that does not have any branches leading outwards. It is called an input node because it is often considered as the starting point or the source of information in a graph.
Output Node:
On the other hand, an output node, also known as a sink node or a leaf node, is a node in a graph that has only outgoing branches. It is a node that does not have any branches leading inwards but only leads to other nodes. It is called an output node because it is often considered as the end point or the destination of information in a graph.
Example:
For example, let's consider a simple graph where nodes A, B, C, and D are connected through branches. If node A has branches leading to nodes B, C, and D, while nodes B, C, and D have branches leading to other nodes but not back to node A, then node A is an input node, and nodes B, C, and D are output nodes.
In this case, the correct answer is option 'A' because an input node is the term used to describe a node that has only incoming branches.
Signal flow graph is a - a)semilog graph
- b)log-log graph
- c)topological representation of a set of differential equations
- d)a special type of graph for analysis of modern control system
Correct answer is option 'C'. Can you explain this answer?
Signal flow graph is a
a)
semilog graph
b)
log-log graph
c)
topological representation of a set of differential equations
d)
a special type of graph for analysis of modern control system
 | Kanika Nair answered |
Understanding Signal Flow Graphs
Signal flow graphs (SFGs) provide a visual representation of the relationships between variables in a system of linear equations, particularly useful in control systems and signal processing. They serve as a powerful tool for analyzing the interconnections between system components.
Key Features of Signal Flow Graphs:
- Topological Representation:
- SFGs illustrate the flow of signals in a system using nodes and directed edges, where nodes represent variables (signals) and edges represent the relationships (functions) between these variables.
- Node and Branch Concept:
- Each node corresponds to a variable (input, output, or state), while branches indicate how signals influence one another. The direction of the branches indicates the flow of the signal.
- Simplification of Complex Systems:
- SFGs allow engineers to simplify complex systems and easily identify feedback loops and interactions, facilitating the analysis of system behavior.
Applications of Signal Flow Graphs:
- Control Systems:
- In modern control system design, SFGs are used to derive transfer functions and calculate system responses analytically.
- Signal Processing:
- SFGs help in understanding and designing filters and other signal processing components.
- Graphical Representation:
- They provide an intuitive understanding of how signals propagate through a system, making it easier to visualize interactions.
Conclusion:
In essence, the correct answer to the question is option 'C' because a signal flow graph is indeed a topological representation of a set of differential equations, encapsulating the dynamics of the system in a clear and systematic manner. This representation is pivotal in modern control and signal processing disciplines.
Signal flow graphs (SFGs) provide a visual representation of the relationships between variables in a system of linear equations, particularly useful in control systems and signal processing. They serve as a powerful tool for analyzing the interconnections between system components.
Key Features of Signal Flow Graphs:
- Topological Representation:
- SFGs illustrate the flow of signals in a system using nodes and directed edges, where nodes represent variables (signals) and edges represent the relationships (functions) between these variables.
- Node and Branch Concept:
- Each node corresponds to a variable (input, output, or state), while branches indicate how signals influence one another. The direction of the branches indicates the flow of the signal.
- Simplification of Complex Systems:
- SFGs allow engineers to simplify complex systems and easily identify feedback loops and interactions, facilitating the analysis of system behavior.
Applications of Signal Flow Graphs:
- Control Systems:
- In modern control system design, SFGs are used to derive transfer functions and calculate system responses analytically.
- Signal Processing:
- SFGs help in understanding and designing filters and other signal processing components.
- Graphical Representation:
- They provide an intuitive understanding of how signals propagate through a system, making it easier to visualize interactions.
Conclusion:
In essence, the correct answer to the question is option 'C' because a signal flow graph is indeed a topological representation of a set of differential equations, encapsulating the dynamics of the system in a clear and systematic manner. This representation is pivotal in modern control and signal processing disciplines.
Signal flow graphs are reliable to find transfer function than block diagram reduction technique.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
Signal flow graphs are reliable to find transfer function than block diagram reduction technique.
a)
True
b)
False
 | Anirban Gupta answered |
Introduction
Signal flow graphs (SFGs) and block diagrams are both tools used in control systems and electrical engineering to represent and analyze systems. However, signal flow graphs provide certain advantages that make them more reliable for finding transfer functions.
Advantages of Signal Flow Graphs
- Visualization of Relationships: SFGs clearly represent the relationships between variables in a system, making it easier to visualize how inputs affect outputs.
- Direct Application of Mason's Gain Formula: Signal flow graphs allow for the direct application of Mason's Gain Formula, which simplifies the calculation of transfer functions by considering all paths and loops in the graph.
- Ease of Handling Complex Systems: For complex systems with multiple feedback loops, SFGs can be more straightforward to analyze, as they do not require tedious block diagram reductions.
- Reduction of Errors: The graphical nature of SFGs helps in minimizing errors that may occur during manual calculations in block diagram reduction.
Block Diagram Limitations
- Complexity in Reduction: Block diagrams often require multiple steps of reduction, which can lead to mistakes and make the process cumbersome, especially for intricate systems.
- Less Intuitive: While block diagrams are useful, they can be less intuitive than SFGs in conveying the overall system dynamics, particularly for those unfamiliar with the method.
Conclusion
In conclusion, while both methods have their uses, signal flow graphs are generally more reliable for finding transfer functions due to their visual clarity, ease of complex system handling, and reduced potential for errors. Thus, the statement is true.
Signal flow graphs (SFGs) and block diagrams are both tools used in control systems and electrical engineering to represent and analyze systems. However, signal flow graphs provide certain advantages that make them more reliable for finding transfer functions.
Advantages of Signal Flow Graphs
- Visualization of Relationships: SFGs clearly represent the relationships between variables in a system, making it easier to visualize how inputs affect outputs.
- Direct Application of Mason's Gain Formula: Signal flow graphs allow for the direct application of Mason's Gain Formula, which simplifies the calculation of transfer functions by considering all paths and loops in the graph.
- Ease of Handling Complex Systems: For complex systems with multiple feedback loops, SFGs can be more straightforward to analyze, as they do not require tedious block diagram reductions.
- Reduction of Errors: The graphical nature of SFGs helps in minimizing errors that may occur during manual calculations in block diagram reduction.
Block Diagram Limitations
- Complexity in Reduction: Block diagrams often require multiple steps of reduction, which can lead to mistakes and make the process cumbersome, especially for intricate systems.
- Less Intuitive: While block diagrams are useful, they can be less intuitive than SFGs in conveying the overall system dynamics, particularly for those unfamiliar with the method.
Conclusion
In conclusion, while both methods have their uses, signal flow graphs are generally more reliable for finding transfer functions due to their visual clarity, ease of complex system handling, and reduced potential for errors. Thus, the statement is true.
Signal flow graphs:- a)They apply to linear systems
- b)The equation obtained may or may not be in the form of cause or effect
- c)Arrows are not important in the graph
- d)They cannot be converted back to block diagram
Correct answer is option 'A'. Can you explain this answer?
Signal flow graphs:
a)
They apply to linear systems
b)
The equation obtained may or may not be in the form of cause or effect
c)
Arrows are not important in the graph
d)
They cannot be converted back to block diagram
 | Mihir Khanna answered |
Explanation: Signal flow graphs are used to find the transfer function of control system by converting the block diagrams into signal flow graphs or directly but cannot be used for nonlinear systems.
The relationship between an input and output variable of a signal flow graph is given by the net gain between the input and output node is known as the overall______________- a)Overall gain of the system
- b)Stability
- c)Bandwidth
- d)Speed
Correct answer is option 'A'. Can you explain this answer?
The relationship between an input and output variable of a signal flow graph is given by the net gain between the input and output node is known as the overall______________
a)
Overall gain of the system
b)
Stability
c)
Bandwidth
d)
Speed
 | Vaishnavi Nair answered |
Explanation: The relationship between input and output variable of a signal flow graph is the overall gain of the system.
Assertion (A): Signal flow graph is applicable to the linear systems.
Reason (R): Signal flow graph method of finding the transfer function of a system is very simple and does not require any reduction technique.- a)Both A and R are true and R is a correct explanation of A.
- b)Both A and R are true but R is not a correct explanation of A.
- c)A is true but R is false.
- d)A is false but R is true.
Correct answer is option 'B'. Can you explain this answer?
Assertion (A): Signal flow graph is applicable to the linear systems.
Reason (R): Signal flow graph method of finding the transfer function of a system is very simple and does not require any reduction technique.
Reason (R): Signal flow graph method of finding the transfer function of a system is very simple and does not require any reduction technique.
a)
Both A and R are true and R is a correct explanation of A.
b)
Both A and R are true but R is not a correct explanation of A.
c)
A is true but R is false.
d)
A is false but R is true.
 | Keerthana Pillai answered |
Signal flow graph is applicable to the linear systems because output is proportional to gain of the system
Reason (R) is also true but is not a correct explanation of assertion (A)
Reason (R) is also true but is not a correct explanation of assertion (A)
A signal flow graph is the graphical representation of the relationships between the variables of set linear algebraic equations.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
A signal flow graph is the graphical representation of the relationships between the variables of set linear algebraic equations.
a)
True
b)
False
 | Parth Ghoshal answered |
Explanation: By definition signal flow graphs are the graphical representation of the relationships between the variables of set linear algebraic equations.
The signal flow graph shown below has M number of forward path and N number of individual loops.
Q. What are the values of M and N ?- a)M= 3 and N= 4
- b)M = 4 and N = 6
- c)M = 3 and N = 6
- d)M = 4 and N =3
Correct answer is option 'A'. Can you explain this answer?
The signal flow graph shown below has M number of forward path and N number of individual loops.
Q. What are the values of M and N ?
Q. What are the values of M and N ?
a)
M= 3 and N= 4
b)
M = 4 and N = 6
c)
M = 3 and N = 6
d)
M = 4 and N =3
 | Gate Gurus answered |
There are three forward paths. The gain of the forward path are:
- M1 = G1G2G3G4G5
- M2 = G1G6G4G5
- M3 = G1G2G7
There are four loops with loop gains:
N1= - G4H1
N1= - G4H1
N2= - G2G7H2
N3= - G6G4G5H2
N4= - G2G3G4G5H2
Mason's rule is applied to- a)signal flow graph
- b)rotational system
- c)block diagram reduction technique
- d)both (a) and (b)
Correct answer is option 'A'. Can you explain this answer?
Mason's rule is applied to
a)
signal flow graph
b)
rotational system
c)
block diagram reduction technique
d)
both (a) and (b)
 | Keerthana Chauhan answered |
Mason's rule or Mason’s gain formula is applied to signal flow graph for finding the transfer function.
A node having only outgoing branches.- a)Input node
- b)Output node
- c)Incoming node
- d)Outgoing node
Correct answer is option 'A'. Can you explain this answer?
A node having only outgoing branches.
a)
Input node
b)
Output node
c)
Incoming node
d)
Outgoing node
| | Sanya Agarwal answered |
Nodes are the point by which the branches are outgoing or ingoing and this can be input or output node and input node is the node having only outgoing branches.
Consider the following statements:
1. Transfer function is an expression which relates output to input in s-domain.
2. Transfer function gives information about the internal structure of the system.
3. A system can be represented by the block diagram if the transfer function of the system is known.
4. Block diagram is the flow of system variables from one block to another block represented by a single line.Q. Which of the above statements is/are true?- a)3 and 4 only
- b)1,3 and 4 only
- c)1, 2 and 4 only
- d)1,2, 3 and 4
Correct answer is option 'B'. Can you explain this answer?
Consider the following statements:
1. Transfer function is an expression which relates output to input in s-domain.
2. Transfer function gives information about the internal structure of the system.
3. A system can be represented by the block diagram if the transfer function of the system is known.
4. Block diagram is the flow of system variables from one block to another block represented by a single line.
1. Transfer function is an expression which relates output to input in s-domain.
2. Transfer function gives information about the internal structure of the system.
3. A system can be represented by the block diagram if the transfer function of the system is known.
4. Block diagram is the flow of system variables from one block to another block represented by a single line.
Q. Which of the above statements is/are true?
a)
3 and 4 only
b)
1,3 and 4 only
c)
1, 2 and 4 only
d)
1,2, 3 and 4
 | Bijoy Nair answered |
Transfer function does not gives information about the internal structure of the system. Hence, staement-2 is false.
Loop which do not possess any common node are said to be ___________ loops.- a)Forward gain
- b)Touching loops
- c)Non touching loops
- d)Feedback gain
Correct answer is option 'C'. Can you explain this answer?
Loop which do not possess any common node are said to be ___________ loops.
a)
Forward gain
b)
Touching loops
c)
Non touching loops
d)
Feedback gain
| | Arya Mukherjee answered |
Explanation: Loop is the part of the network in which the branch starts from the node and comes back to the same node and non touching loop must not have any node in common.
By performing cascading and/or summing/differencing operations using transfer function blocks G1(s) and G2(s), one CANNOT realize a transfer function of the form- a)G1(s) G2(s)
- b)G1(s) / G2(s)
- c)G1(s)(1/G1(s) + G2(s))
- d)G1(s)(1/G1(s) - G2(s))
Correct answer is option 'B'. Can you explain this answer?
By performing cascading and/or summing/differencing operations using transfer function blocks G1(s) and G2(s), one CANNOT realize a transfer function of the form
a)
G1(s) G2(s)
b)
G1(s) / G2(s)
c)
G1(s)(1/G1(s) + G2(s))
d)
G1(s)(1/G1(s) - G2(s))
 | Yashvi Mathur answered |
Understanding Transfer Function Realizations
In control systems, transfer functions represent the relationship between input and output in the Laplace domain. Given two transfer functions G1(s) and G2(s), we can perform various operations to realize new transfer functions.
Operations Overview
- Cascading: This involves connecting the output of one block to the input of another, resulting in multiplication of their transfer functions (G1(s) * G2(s)).
- Summing/Differencing: This operation allows for the addition or subtraction of outputs, leading to combinations that can be expressed as functions of G1(s) and G2(s).
Evaluating Each Option
- Option A: G1(s) * G2(s)
This is achievable through cascading, where the output of G1 feeds into G2.
- Option B: G1(s) / G2(s)
This operation indicates a division of transfer functions. Standard cascading and summing/differencing operations cannot directly produce a division. Instead, division typically requires a feedback or more complex configurations not available through basic operations.
- Option C: G1(s)(1/G1(s) + G2(s))
This can be simplified and realized through summing, making it feasible.
- Option D: G1(s)(1/G1(s) - G2(s))
Similar to option C, this expression can also be realized through summing and manipulating transfer functions.
Conclusion
Thus, the only operation that cannot be realized through cascading or summing/differencing is Option B: G1(s) / G2(s), as it requires division, which is not achievable by the stated operations.
In control systems, transfer functions represent the relationship between input and output in the Laplace domain. Given two transfer functions G1(s) and G2(s), we can perform various operations to realize new transfer functions.
Operations Overview
- Cascading: This involves connecting the output of one block to the input of another, resulting in multiplication of their transfer functions (G1(s) * G2(s)).
- Summing/Differencing: This operation allows for the addition or subtraction of outputs, leading to combinations that can be expressed as functions of G1(s) and G2(s).
Evaluating Each Option
- Option A: G1(s) * G2(s)
This is achievable through cascading, where the output of G1 feeds into G2.
- Option B: G1(s) / G2(s)
This operation indicates a division of transfer functions. Standard cascading and summing/differencing operations cannot directly produce a division. Instead, division typically requires a feedback or more complex configurations not available through basic operations.
- Option C: G1(s)(1/G1(s) + G2(s))
This can be simplified and realized through summing, making it feasible.
- Option D: G1(s)(1/G1(s) - G2(s))
Similar to option C, this expression can also be realized through summing and manipulating transfer functions.
Conclusion
Thus, the only operation that cannot be realized through cascading or summing/differencing is Option B: G1(s) / G2(s), as it requires division, which is not achievable by the stated operations.
The poles of the transfer function C(s)/R(s) of the system represented by the block diagram shown below are located at
- a)0, -2 and -4
- b)-1, -2 and -4
- c)-2, -3 and -4
- d)-1 , -2 and -3
Correct answer is option 'D'. Can you explain this answer?
The poles of the transfer function C(s)/R(s) of the system represented by the block diagram shown below are located at
a)
0, -2 and -4
b)
-1, -2 and -4
c)
-2, -3 and -4
d)
-1 , -2 and -3
| | Saumya Basak answered |
The given block diagram can be reduced as shown below.
The transfer function C(s) / R(s) for the block diagram shown below is
- a)
- b)
- c)
- d)
Correct answer is option 'C'. Can you explain this answer?
The transfer function C(s) / R(s) for the block diagram shown below is
a)
b)
c)
d)
 | Sandeep Saha answered |
Combining the blocks in parallel, the block diagram is reduced as shown below.
Which one of the following block diagrams in options given is equivalent to the below shown block diagram?
- a)
- b)
- c)
- d)None of the above
Correct answer is option 'D'. Can you explain this answer?
Which one of the following block diagrams in options given is equivalent to the below shown block diagram?
a)
b)
c)
d)
None of the above
| | Shivam Ghosh answered |
The T.F. of the given block diagram can be reduced to: 
Its block diagram is shown below, where a closed loop feedback system is transformed into an unity feedback system and vice-versa,
Its block diagram is shown below, where a closed loop feedback system is transformed into an unity feedback system and vice-versa,
The gain C(s)/R(s) of the signal flow graph shown below is
- a)
- b)
- c)
- d)
Correct answer is option 'D'. Can you explain this answer?
The gain C(s)/R(s) of the signal flow graph shown below is
a)
b)
c)
d)
| | Mira Menon answered |
Gain of forward paths are:
P1 = G1G2G3 and P2 = G4
Here, Δ1 = 1
and Δ2 = (1 + G1G2— G2G3)
Individual loops are:
L1 = -G1G2
and L2 = G2G3
Non-touching loop = Nil
P1 = G1G2G3 and P2 = G4
Here, Δ1 = 1
and Δ2 = (1 + G1G2— G2G3)
Individual loops are:
L1 = -G1G2
and L2 = G2G3
Non-touching loop = Nil
Use mason’s gain formula to calculate the transfer function of given figure:
- a)G1/1+G2H
- b)G1+G2/1+G1H
- c)G2/1+G1H
- d)None of the mentioned
Correct answer is option 'B'. Can you explain this answer?
Use mason’s gain formula to calculate the transfer function of given figure:
a)
G1/1+G2H
b)
G1+G2/1+G1H
c)
G2/1+G1H
d)
None of the mentioned
| | Swati Shah answered |
Explanation: Use mason’s gain formula to solve the signal flow graph and by using mason’s gain formula transfer function from signal flow graph can be calculated which relates the forward path gain to the various paths and loops.
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