The equation for voltage waveform v(t) shown below is (where u(t) is unit step input) :

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  1. u(t − 1) + u(t − 2) + u(t − 3) 
  2. u(t − 1) + 2u(t − 2) + 3u(t − 3)
  3. u(t − 1) − u(t − 2) − u(t − 3) + 3u(t − 4) 
  4. u(t − 1) +u(t − 2) +u(t − 3) − 3u(t − 4)

Answer (Detailed Solution Below)

Option 4 : u(t − 1) +u(t − 2) +u(t − 3) − 3u(t − 4)
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Detailed Solution

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Concept:

The voltage waveform can be expressed using unit step functions (u(t)) to represent the changes in voltage at specific time intervals. Each step in the waveform corresponds to the addition or subtraction of a unit step function at the respective time.

Calculation:

Given:

Voltage waveform with the following characteristics:
- Starts at 0V
- Jumps to 1V at t=1
- Jumps to 2V at t=2
- Jumps to 3V at t=3
- Returns to 0V at t=4

Solution:

1. The waveform can be constructed as:

2. This represents:

  • +1V step at t=1
  • +1V step at t=2 (total 2V)
  • +1V step at t=3 (total 3V)
  • -3V step at t=4 (return to 0V)

 

Final Answer:

The correct equation is 4) u(t − 1) +u(t − 2) +u(t − 3) − 3u(t − 4)

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