4. An RC coupled amplifier has an open loop gain of 200 and a lower cutoff frequency of 50 Hz. If negative feedback with ? = 0.1 is used, the lower cut off frequency will be
A feedback amplifier is stable if loop gain is less than unity. More less, more stable, hence ? will be more stable.
10. A bridge rectifier circuit has input of 50 Hz frequency. The load resistance is RL and filter capacitance is C. For good output wave shape, the time constant RLC should be at least equal to