Assertion (A): A large negative feedback is deliberately introduced in an amplifier to make its gain independent of variation in parameters of active device.

Reason (R): A large negative value of feedback results in a high value of return difference compared to unity which makes the feedback gain inversely proportional to the feedback factor.

The open loop frequency response of a unity feed back system is as under

The gain margin and phase margin respectively are

For underdamped second order systems the rise time is the time required for the response to rise from

The phase angle of is constant and equal to - 90° for all values of ω

Assertion (A): The part of root locus on the real axis is not dependent on the poles and zeros which are not on the real axis.

Reason (R): Poles and zeros which are not on the real axis occur in conjugate pairs