Question
A series $\text{LCR}$ circuit is connected across an $a.c.$ source of variable angular frequency $' \omega'$. Plot a graph showing variation of current $‘i\ ’$ as a function of $' \omega'$ for two resistances $R_1$ and $R2 \ (R_1 > R_2).$
Answer the following questions using this graph:
  1. In which case is the resonance sharper and why?
  2. In which case is the power dissipation more and why?

Answer

  1. Sharper for $R = R_2$
  2. Sharpness of resonance $ = \frac{\omega_{\circ}\text{L}}{\text{R}}\propto\frac{1}{\text{R}}.$
  3. More power dissipation for $\text{R} = \text{R}_{2}$
  4. At Resonance, power dissipation $ = \frac{\text{V}^{2}}{\text{R}}\propto\frac{1}{\text{R}} ($for same $V).$

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

Similar questions

  1. Distinguish between a conductor and a semi conductor on the basis of energy band diagram.
  2. The following figure shows the input waveforms (A, B) and the output waveform (Y) of a gate. Identify the gate, write its truth table and draw its logic symbol.
An ideal gas $\Big(\frac{\text{C}_\text{P}}{\text{C}_\text{V}}=\gamma\Big)$ is taken through a process in which the pressure and the volume vary as $p = aV^b.$ Find the value of $b$ for which the specific heat capacity in the process is zero.
Explain how $p-n$ junction is formed.
A long, cylindrical tube of inner and outer radii a and b carries a current i distributed uniformly over its cross section. Find the magnitude of the magnetic field at a point (a) just inside the tube (b) just outside the tube.
A spherical shell made of plastic, contains a charge Q distributed uniformly over its surface. What is the electric field inside the shell? If the shell is hammered to deshape it without altering the charge, will the field inside be changed? What happens if the shell is made of a metal?
Let $A_{1 }A_{2 }A_3 A_4 A_5 A_6 A_1$ be a regular hexagon. Write the $x-$ components of the vectors represented by the six sides taken in order. Use the fact that the resultant of these six vectors is zero, to prove that$\cos0+\cos\frac{\pi}{3}+\cos\frac{2\pi}{3}+\cos\frac{3\pi}{3}+\cos\frac{4\pi}{3}+\cos\frac{5\pi}{3}=0.$
Use the known cosine values to verify the result.
In a photodiode, the conductivity increases when the material is exposed to light. It is found that the conductivity changes only if the wavelength is less than 620nm. What is the band gap?
Find the angle of deviation suffered by the light ray shown in figure. The refractive index $\mu=1.5$ for the prism material.
i. Differentiate between three segments of a transistor on the basis of their size and level of doping.
ii. When is a transistor said to be in active state?
iii. Draw a plot of transfer characteristic ($V _0$ vs. $V _{ i }$ ) and show which portion of the characteristic is used in amplification and why?
iv. Draw the circuit diagram of the base bias transistor amplifier in CE configuration and briefly explain its working.
  1. Show using a proper diagram how unpolarised light can be linearly polarised by reflection from a transparent glass surface.
  2. The figure shows a ray of light falling normally on the face $AB$ of an equilateral glass prism having refractive index $\frac{3}{2},$ placed in water of refractive index $\frac{4}{3}.$ Will this ray suffer total internal reflection on striking the face $AC$? Justify your answer.