Download App

Alternating Current — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current3 Marks
Question
A series LCR circuit is connected to an ac source. Using the phasor diagram, derive the expression for the impedance of the circuit. Plot a graph to show the variation of current with frequency of the source, explaining the nature of its variation.
✓

Answer



Resultant potential across LCR

$\text{V}^{2} = \text{V}^{2}_{\text{R}} + (\text{V}_{L} - \text{V}_{c} ) ^{2}$

$\text{V}_{R} = \text{iR},\text{V}_{L} = \text{i}\text{X}_{L},\text{V}_\text{c} = \text{i X}_{c}$

On solving

$\text{Z} = \sqrt{\text{R}^{2} + (\text{X}_{L} - \text{X}_{C})^{2}}$


With increase in ω, current first increases (up to ωo ) and then decreases.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Alternating Current→Alternating Current — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

  1. A student wants to use two p-n junction diodes to convert alternating current into direct current. Draw the labelled circuit diagram she would use and explain how it works.
  2. Give the truth table and circuit symbol for NAND gate.
→
The drift current in a reverse-biased p-n junction increases in magnitude if the temperatu,re of the junction is increased. Explain this on the basis of creation of hole-electron pairs.
→
A particle moves in a circle of radius 1.0cm at a speed given by v = 2.0t where v is in cm/s and t in seconds.
  1. Find the radial acceleration of the particle at t = 1s.
  2. Find the tangential acceleration at t = 1s.
  3. Find the magnitude of the acceleration at t = 1s.
→
  1. Define ‘activity’ of a radioactive substance.
  2. Two different radioactive elements with half lives T1 and T2 have N1 and N2 undecayed atoms respectively present at a given instant. Derive an expression for the ratio of their activities at this instant in terms of N1 and N2.
→
Is it easier to take out a nucleon from carbon or from iron? Fi-om iron or from lead?
→
Magnitude of electric field of a plane electromagnetic wave is $40 V / m$ and it vibrates with a frequency of $2 \times 10^{10} s^{-1}$. Calculate the wavelength of the wave.
→
When light of appropriate frequency is shone on two metals X and Y , photo-electrons are emitted from them. The work function of metal X is more than work function of metal Y. For which metal the threshold frequency will be greater and why?
→
Figure shows a metallic rod PQ of length l, resting on the smooth horizontal rails AB positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutually perpendicular directions. A galvanometer G connects the rails through a switch K. Assume the magnetic field to be uniform. Given the resistance of the closed-loop containing the rod is R.
Image

i. Suppose K is open and the rod is moved with a speed v in the direction shown. Find the polarity and magnitude of induced emf.
ii. With K open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience a magnetic force due to the motion of the rod. Explain.
iii. What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular?
→
(i) What is meant by electric power? Prove that $P=\frac{V^2}{R}$ or $P=I^2 R$. Define one-watt electric power.(ii) Define electric energy. Prove that $P = I ^2 R \Delta t$
→
A uniform conducting wire of length 12a and resistance R is wound up as a current carrying coil in the shape of:
  1. An equilateral triangle of side a.
  2. A square of sides a.
  3. A regular hexagon of sides a. The coil is connected to a voltage source V0. Find the magnetic moment of the coils in each case.
→