Signals and Systems - Online Test
Q1. Consider a continuous-time system with input x(t) and output y(t) given by
y(t) = x(t) cos(t)
This system is
Answer : Option C
Explaination / Solution:
Q2. 
A parallel plate capacitor consisting two dielectric materials is shown in the figure. The middle dielectric slab is place symmetrically with respect to the plates.
If the potential difference between one of the plates and the nearest surface of dielectric
interface is 2Volts, then the ratio ε1:ε2 is
Answer : Option C
Explaination / Solution:
Q3. Suppose x1(t) and x2(t) have the Fourier transforms as shown below
Which one of the following statements is TRUE?
Answer : Option C
Explaination / Solution:
Q4. 
Assuming an ideal transformer,. The Thevenin’s equivalent voltage and impedance as seen from the terminals x and y for the circuit in figure are
Answer : Option A
Explaination / Solution:
Q5. The output of a continuous-time, linear time-invariant system is denoted by T{x(t)} where x(t) is
the input signal. A signal z(t) is called eigen-signal of the system T , when T{z(t)} = γz(t),
where γ is a complex number, in general, and is called an eigenvalue of T. Suppose the impulse
response of the system T is real and even. Which of the following statements is TRUE?
Answer : Option D
Explaination / Solution:
Q6. The voltage across the capacitor, as sown in the figure, is expressed as 
The value of A1 and A2 respectively, are
Answer : Option A
Explaination / Solution:
Q7. Consider a causal LTI system characterized by differential equation 
The response of the system to the input 
where u(t) denotes the unit step
function, is
The response of the system to the input where u(t) denotes the unit step
function, is
Answer : Option D
Explaination / Solution:
Q8. Suppose that resistors R1 and R2 are connected in parallel to give an equivalent resistor R. If
resistors R1 and R2 have tolerance of 1% each., the equivalent resistor R for resistors R1 =
300Ω and R2 = 200Ω will have tolerance of
Answer : Option B
Explaination / Solution:
Q9. Consider the function ݂f(z) = z + z* where z is a complex variable and z* denotes its complex
conjugate. Which one of the following is TRUE?
Answer : Option B
Explaination / Solution:
Q10. In the following circuit, the input voltage Vin is 100
sin(100πt). For 100πRC = 50, the
average voltages across R (in volts) under steady-state is nearest to
Answer : Option C
Explaination / Solution:
Given circuit is voltage doubler
Vm = Voltage across each capacitor = 100V
Voltage across two capacitors (in steady state)
= 2Vm = 200V
