GATE EE 2013


Question 1
In the circuit shown below what is the output voltage (V_{out}) if a silicon transistor Q and an ideal op-amp are used?
A
-15 V
B
-0.7 V
C
+0.7 V
D
+15 V
Analog Electronics   Operational Amplifiers
Question 1 Explanation: 


Using the concept of vitual ground, V=0

V_{out}=-0.7V
Question 2
The transfer function \frac{V_{2}(s)}{V_{1}(s)} of the circuit shown below is
A
\frac{0.5s+1}{s+1}
B
\frac{3s+6}{s+2}
C
\frac{s+2}{s+1}
D
\frac{s+1}{s+2}
Control Systems   Mathematical Models of Physical Systems
Question 2 Explanation: 


\frac{V_2(s)}{V_1(s)}=\frac{R+\frac{1}{Cs}}{\frac{1}{Cs}+R+\frac{1}{Cs}}
=\frac{1+RCs}{2+RCs}
=\frac{1+10 \times 10^3 \times 100 \times 10^{-6}s}{2+10 \times 10^3 \times 100 \times 10^{-6}s}
=\frac{s+1}{s+2}


Question 3
Assuming zero initial condition, the response y(t) of the system given below to a unit step input u(t) is
A
u(t)
B
tu(t)
C
\frac{t^{2}}{2}u(t)
D
e^{-t}u(t)
Signals and Systems   Laplace Transform
Question 3 Explanation: 
\begin{aligned} Y(s)&=\frac{1}{s}U(s)=\frac{1}{s^2}\\ y(t)&=tu(t) \end{aligned}
Question 4
The impulse response of a system is h(t)=tu(t). For an input u(t-1), the output is
A
\frac{t^{2}}{2}u(t)
B
\frac{t(t-1)}{2}u(t-1)
C
\frac{(t-1)^{2}}{2}u(t-1)
D
\frac{t^{2}-1}{2}u(t-1)
Signals and Systems   Linear Time Invariant Systems
Question 4 Explanation: 
\begin{aligned} h(t) &=tu(t) \\ H(s) &=\frac{1}{s^2} \\ \Rightarrow \; \frac{Y(s)}{U(s)} &=\frac{1}{s^2} \\ Y(s) &=\frac{1}{s^2} \frac{e^{-s}}{s}\\ \Rightarrow \; y(t) &=\frac{(t-1)^2}{2}u(t-1) \end{aligned}
Question 5
Which one of the following statements is NOT TRUE for a continuous time causal and stable LTI system?
A
All the poles of the system must lie on the left side of the j \omega axis
B
Zeros of the system can lie anywhere in the s-plane
C
All the poles must lie within |s| = 1
D
All the roots of the characteristic equation must be located on the left side of the j \omega axis.
Signals and Systems   Laplace Transform
Question 5 Explanation: 
All poles must lie within |Z|=1




There are 5 questions to complete.