This question was asked inGPSC Deputy Executive Engineer (Electrical) Class-2 Master Paper 2026Question 117 of 195 published · Gujarat Public Service CommissionOpen paper
Q117ModerateTransfer Function & Modelling

Consider the following statements regarding Transfer Function:
1. Transfer function is defined as ratio of Laplace transform of output to input under zero initial conditions.
2. It provides complete information about system internal states.
3. Poles of transfer function determine system stability.
4. Zeros influence transient and frequency response characteristics.
Which of the above statements is/are correct?

Answer & step-by-step solution
Correct answer: D. 1, 3 and 4 only
Quick explanation

A transfer function is the Laplace-domain ratio of output to input for a linear time-invariant system under zero initial conditions. Its poles and zeros determine important input-output stability, transient and frequency-response features, but the transfer function does not uniquely reveal the internal state realization. Key relation: G(s)=Y(s)/U(s) with zero initial conditions.

Exam focus: Poles are denominator roots; zeros are numerator roots. Common trap: Transfer functions do not contain complete unique internal-state information.

G(s)=Y(s)/U(s) with zero initial conditions.

Statement-wise Verification

  • Statement 1 - Correct.
    Transfer function is defined as ratio of Laplace transform of output to input under zero initial conditions.
    A transfer function is the Laplace-domain ratio of output to input for a linear time-invariant system under zero initial conditions.
  • Statement 2 - Incorrect.
    It provides complete information about system internal states.
    A transfer function describes input-output behavior under zero initial conditions and does not uniquely reveal internal state realization
  • Statement 3 - Correct.
    Poles of transfer function determine system stability.
    Its poles and zeros determine important input-output stability, transient and frequency-response features, but the transfer function does not uniquely reveal the internal state realization.
  • Statement 4 - Correct.
    Zeros influence transient and frequency response characteristics.
    Its poles and zeros determine important input-output stability, transient and frequency-response features

Core Concept

A transfer function is the Laplace-domain ratio of output to input for a linear time-invariant system under zero initial conditions. Its poles and zeros determine important input-output stability, transient and frequency-response features, but the transfer function does not uniquely reveal the internal state realization.

Formula / Key Relationship

G(s)=Y(s)/U(s) with zero initial conditions.

Why the Other Options Are Wrong

Option A is incorrect because it includes incorrect statement(s) 2 and omits correct statement(s) 4. Option B is incorrect because it omits correct statement(s) 4. Option C is incorrect because it includes incorrect statement(s) 2 and omits correct statement(s) 1, 4.

Exam Shortcut / Approach

Poles are denominator roots; zeros are numerator roots.

Common Mistake

Transfer functions do not contain complete unique internal-state information.

Quick Revision

Poles Zeros and Zero Initial Conditions is linked with Transfer Function, System Modeling and Control Systems. Poles are denominator roots; zeros are numerator roots.

Exam tipPoles are denominator roots; zeros are numerator roots.
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