BE Mechanical Engineering सत्र २ (इंजीनियरिंग) - University of Mumbai Important Questions

With a neat energy level diagram describe the construction and working of He-Ne Laser. What are the merits and demerits?

Differentiate between spontaneous and stimulated emission.

What is Numerical aperture? Explain the use of optical fibre in temperature sensor. The core diameter of a multimode step index fibre is 50 μm. The numerical aperture is 0.25. Calculate the number of guided modes at an operating wavelength of 0.75 μm. 

The core diameter of multimode step index fibre is 50 μm.The numerical aperture is 0.25. Calculate the number of guided modes at an operating wavelength of 0.75 μm.

Difference between step index and graded index fibre.

An optical fibre has a numerical aperture of 0.20 and refractive index of cladding is 1.59. Determine the core refractive index and the acceptance angle for the fibre in water which has a refractive index of 1.33.

Derive the formula for numerical aperture of step index fibre and give it’s physical significance.The N.A of of an optical fibre is 0.5 and the core refractive index is 1.54.Find the refractive index of cladding.

A glass material A with an optical fibre is made has a refractive index of 1.55. This material is clad with another material whose refractive index is 1.51. The light in the fibre is launched from air. Calculate the numerical aperture of the fibre.

What is monomode and multimode fibre? Explain the term V-number, Calculate the number of modes of a step index optical fibre of diameter 40 𝝁𝒎 will transmit as its core and cladding refractive indices are 1.5 and 1.46 respectively. Wavelength of light used is 1.5 𝝁𝒎.

Draw the block diagram of an optical fibre communication system and explain function of each block.

Show that the divergence of curl of a vector is zero.

Explain spherical co-ordinate system. State the transformation relation between Cartesian and spherical co-ordinates.

Derive Maxwell’s two general equations in integral and differential form. 

What is a divergence of a vector field? Express it in cartesian co-ordinate system.

Explain cylindrical co-ordinate system.
State the transformation relation between cartesian and cylindrical co-ordinates.

Using spherical co-ordinate systems calculate the area of a disc of radius 2 cm.

Find cylindrical co-ordinates of a point (3𝒊̅ + 4𝒋̅ + 𝒌̅) 

Find the divergence of vector field F=x2yz𝒊 ̅+ xz𝒋̅

Write Maxwell’s equation and give its physical significance.

Find the divergence of the vector function A=x² i+x²y² j+24x²y²z³ k.

Derive Maxwell’s Third Equation.