Derive an expression for the Poynting's vector and explain us significance A light source (one kilowatt) is radiating energy uniformly. Determine the intensity of the electric field at a distance of one metre from the sources.
Discuss briefly the various ways of modulation of electromagnetic waves for the purpose of communication through radio and television.
Write down Maxwell s equations for the electromagnetic field in Free space and show that \vec{E} satisfies the wave equation. Hence obtain the expression for the velocity of e.m. waves in free space.
Obtain an expression for the force exerted on unit volume of a paramagnetic substance in a non-uniform magnetic field. How could you experimentally distinguish and diamagnetic and paramagnetic substance?
What is dielectric susceptibility? Describe how you can determine the radius of an atom from the measurement of the dielectric constant of a gas. A parallel plate condenser consists of two plates of area 400\text{ sq. cm.} each separated by a sheet of material of 0.10\text{ mm} thickness. Find the capacity in microfarads when the dielectric constant of the material is 5.0.
In an oscillatory circuit L = 0.30\text{ henry} and C = 1.2 \times 10^{-6}\text{ F,} determine the value of maximum resistance so that the circuit may remain oscillatory.
Write a note on Anomalous dispersion.
Derive an expression for the mean energy \varepsilon of a Planck oscillator in thermal equilibrium with the surroundings. How does the ratio h\nu / kT vary as the temperature T varies from \leqslant h\nu / k to \leqslant h\nu / k, the symbols having the usual meanings?
L and R in series and C in parallel to them.
Two homogeneous isotropic dielectric media have a common plane boundary and ale otherwise infinite in extent. An electromagnetic wave is incident on the boundary. Establish the laws of reflection and refraction.
Calculate the power radiated by a tungsten filament 10 cm long and 0.010 mm in diameter, when it is heated to 2,500 K in an evacuated bulb. Assume that the filament radiates at 30% of the rate of a black body at the same temperature.
Two cells of emf 2 volts each and internal resistance 2 ohms rich are connected in parallel with each other and with a load resistance. Calculate the maximum power that can be dissipated in the load.
L, C and R in series. Discuss the factors that determine sharpness of resonance in these cases.
Obtain an expression for the impedance of an LCR circuit for the following cases:
The parallel plates of a capacitor have an area of 2000\text{ cm}^2 each and are 1\text{ cm} apart. They are originally at a potential difference of 3,000\text{ volts}. When a dielectric is introduced covering the whole space between the plates, the potential difference becomes 1000\text{ volts}. Calculate the capacitance of the capacitor before and after insertion of the dielectric. What is the dielectric constant of the dielectric?
Write a note on Physical significance of each of the four Maxwell's equation.
Write down the expression for the energy distribution of a black body radiation at temperature T and deduce. Wien's displacement law. \frac{h\omega_{m}}{kT} = \text{const.} Taking the constant to be equal to 3-\epsilon, where \epsilon is small (so that \epsilon can be neglected in comparison to 1). Find the value of \epsilon.
