Explain what is laser diodes?

Electrical and Electronic Engineering - Interview Questions

Laser diodes are compact transistor like packages with two or more electrical leads. Lasing occurs when stimulated emission results into the amplification of photon confined to the lasing mode. These photons hit back and forth between the back and front mirror, and hence a diverging beam emits from the laser diode packages.

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What are the advantages of VSCF wind electrical system?

Advantages of VSCF wind electrical system are :

* No complex pitch changing mechanism is needed.
* Aero turbine always keeps going at maximum efficiency point.
* Extra energy in the high wind speed region of the speed – duration curve can be extracted
* Significant reduction in aerodynamic stresses, which are associated with constant – speed operation.

Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv?

Transformer Induced voltage equation contains 4.44 factor.

E=4.44*f*T*phi
E -Induced emf per phase
T -number of turns
f -frequency
phi -maximum flux per pole
From the equation we see that E is proportional to 4.4 and it is in turn multiple of 11.

So always transmission voltage is multiple of 11