Analog Electronics - Study Mode
[#246] In deriving ac equivalent circuit for an amplifier circuit we short circuit
Correct Answer
(D) All capacitors
[#247] Thermal runaway is not possible in FET because as the temperature of FET increases
Correct Answer
(A) The mobility decreases
[#248] The direction of induced e.m.f. can be found by
Correct Answer
(B) Lenz's law
Explanation
Solution: The direction of induced electromotive force (e.m.f.) can be found by Lenz's law . Lenz's law states that the direction of the induced electromotive force (e.m.f.) in a circuit is such that it opposes the change in magnetic flux that causes it. In other words, when there is a change in magnetic flux passing through a coil or a conductor, an e.m.f. is induced in the conductor in a direction that produces a magnetic field opposing the change in the original magnetic field. This law helps to understand the direction of the induced current and the polarity of the induced voltage when a magnetic field is changing in a conductor, coil, or any closed-loop circuit. It is a fundamental principle in electromagnetic induction and is used to analyze and predict the behavior of inductors and transformers in electrical and electronic circuits.
[#249] In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will
Correct Answer
(B) Decrease
Explanation
Solution: In an iron cored coil , the presence of the iron core significantly increases the inductance due to the higher magnetic permeability of iron compared to air. When the iron core is removed , the coil becomes an air cored coil , which has much lower magnetic permeability. As a result, the inductance of the coil will decrease .
[#250] A crack in the magnetic path of an inductor will result in
Correct Answer
(D) Reduced inductance
Explanation
Solution: A crack in the magnetic path of an inductor creates a gap in the core, disrupting the continuous magnetic flux. This disruption increases the reluctance of the magnetic circuit, which reduces the overall inductance of the inductor. As a result, the inductance will be reduced rather than remaining unchanged or increasing.