18 Questions
At resonance in an LC circuit, the electric current is referred to as?
The wattless current
In a series LCR circuit at resonance, how are the applied emf and current related?
In phase
What is the main function of a series LCR resonant circuit?
A tunning circuit in a television receiver set
When AC voltage is applied to a pure capacitor, how does the voltage across the capacitor relate to the current?
Lags the current by phase angle π/2 rad
What is the main purpose of a parallel LC resonant circuit?
A tunning circuit in a television receiver set
What does an electric current in an LC-circuit at resonance represent?
The wattless current
What does Faraday's Law of electromagnetic Induction state?
The induced electromotive force (emf) is proportional to the rate of change of magnetic field strength
What is the mathematical relation between the number of turns in the primary coil to the secondary coil in a step-up transformer?
$N_p = kN_s$ where $k$ is a constant greater than 1
When do we say two coils are perfectly coupled with each other?
When all magnetic field lines are linked with both coils
What is Lenz's Law?
The induced emf always opposes the change in magnetic flux that produced it
A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil varies from 0 to 20 A in 0.5 s, what is the change of flux linked with the other coil?
$15 , \text{Wb}$
An aircraft with a wing span of 50 m flies horizontally in Earth's magnetic field at a speed of 400 m/s. What is the emf generated between the tips of the wings?
$1.2 , \text{V}$
What is the peak value of an alternating source if an electric bulb, which operates at 10 V d.c., connected to it gives normal brightness?
28.28 V
When a coil of resistance 300Ω and inductance 1.0 H is connected to an alternating voltage, what is the phase difference between the voltage and current in the circuit?
45°
What is the angular frequency of free oscillations when a charged 10 micro farad capacitor is connected to an 81 mH inductor?
$1.5 \times 10^3$ rad per sec
What is the condition for current resonance in an LCR series circuit?
Maximum current
State one characteristic of a parallel LC AC resonance circuit.
Minimum bandwidth
What is the relationship between average current and rms current over half a cycle in an AC circuit?
$\frac{1}{\sqrt{2}}$
This quiz covers topics related to A.C circuits, including expressions for power in magnetic fields, Ampere's law, and transformers. It includes long answer questions as well as multiple-choice questions.
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