An oscillator is nothing but an amplifier with


Correct option is

Positive feedback

In an amplifier, externally applied ac input voltage is amplifier at the output. An oscillator produces an output at a desired frequency without any external input voltage. This is achieved providing a positive feedback from a part of the output of the amplifier inj the correct phase to the input circuit of the oscillator. 



At absolute zero of temperature, the electrical conductivity of a pure semiconductor is


In pure silicon at 300 K the electron and hole concentration is each equal to . When doped with indium, the hole concentration increases to . What is the electron concentration in doped silicon?


In a transistor circuit, the collector current is 50 mA and the base current is 1 mA. The current gain  is


In a transistor circuit, the collector current is 9.8 mA and the base current is 10 mA. The current gain  is 


In a transistor amplifier, the two ac current gains  as defined as . The relation between  is


In a transistor, a change of 8.0 mA in the emitter current produces a change of 7.8 mA in the collector current. What change in the base current is necessary to produce the same change in the collector current?


In a common emitter amplifier, the output resistance is  and the input resistance . In the peak value of the signal voltage is 10 mV and , then the peak value of the output voltage is 


The base current of a transistor is  and the collector current is 2 mA. What is the current gain for the common base configuration? 


In the depletion region of an unbiased pn junction diode, there are


When Ge crystals are doped with phosphorus atom, then it becomes