Question

________ a sinusoidal transfer function of a system can be represented by two separate plots, where one plot corresponds to the magnitude vs frequency while the other corresponds to the phase angle vs frequency response of the system.
1. By the use of a bode plot
2. By the use of a root-locus plot
3. By the use of block-diagram representation
4. By the use of signal flow graph

Answer 1

Correct Answer - Option 1 : By the use of a bode plot

A Bode plot is a graph of the frequency response of a system.

It is usually a combination of a Bode magnitude plot, expressing the magnitude (usually in decibels) of the frequency response, and a Bode phase plot, expressing the phase shift.

In a Bode magnitude plot,

• For a pole at the origin, the initial slope is -20 dB/decade
• For a zero at the origin, the initial slope is 20 dB/decade
• The slope of magnitude plot changes at each corner frequency
• The corner frequency associated with poles causes a slope of -20 dB/decade
• The corner frequency associated with poles causes a slope of -20 dB/decade
• The final slope of Bode magnitude plot = (Z - P) × 20 dB/decade

Where Z is the number zeros and P is the number of poles