# MATLAB Questions and Answers – Modeling – 2

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This set of MATLAB Problems focuses on “Modeling – 2”.

1. We _______ simulate circuits in MATLAB.
a) can
b) cannot
c) can, only by blocks
d) can or cannot

Explanation: Not only by blocks, but electronic components are also present in the Simscape toolbox. We can simulate the working of circuits via this toolbox. We would need a source and the scope to generate and view waveforms of input and output respectively.

2. Photodiodes are present in the _________ section of the Simscape toolbox
a) Special Purpose Diodes
b) Semiconductor devices
c) Diodes
d) Sensors

Explanation: It is not present in the section mentioned in semiconductor devices, diodes and special purpose diodes, don’t exist as separate sections. It is really present in the sensors section since it acts like a sensor only.

3. Where is the following block present? a) Nowhere
b) Sink
c) Source
d) Ground

Explanation: This block acts as a source and hence it’s placed in the Source section. This is different from ground.

4. The output in the scope is an analog signal.
a) True
b) False

Explanation: The output of the scope always shows as an analog signal. It is recommended to use other means of realizing digital outputs such as bulbs.

5. The Battery is also viewed as a charge dependent source. a) True
b) False

Explanation: The battery can be modelled with an internal resistance and an internal capacitance. Hence, the above statement is true.

6. We can model __ impulse function in discrete domain
a) No
b) Unit
c) Shifted unit
d) Any

Explanation: The impulse function can be modelled by choice and it doesn’t matter how much we want to delay the impulse function nor the fact that it’s continuous or discrete.

7. What does the following model portray? a) Measuring impulse response of a system
b) Measuring impulse response of a system
c) Measuring ramp response of a system
d) Measuring step response of a system

8. What does the following model show? a) The discrete impulse is shifted by 8 units in time
b) The discrete transfer function is shifted by 8 units in time
c) The output has an error
d) The output does not match the graph

Explanation: The transfer function represents a ramp function. Now, the scope shows a graph starts from t=8 units in time and goes to 1 at t=9. Thus the impulse input given to the graph is actually shifted by 8 units in time.

9. What does this block do? a) Gives a logic 1 if the input is greater than it’s previous value
b) Gives a logic 0 if the input is greater than it’s previous value
c) Gives a logic 1 if the input is smaller than it’s previous value
d) Gives a logic 0 if the output is greater than it’s previous value

Explanation: The above block gives a 1 if the input is strictly greater than it’s previous value. It returns a 0 if the input is less than or equal to it’s previous value, as defined in SIMULINK TOOLBOX.

10. What does this model do? a) Generate a step and ramp function
b) Generate a ramp and parabolic function
c) Generate pulse function
d) Error 