If a semiconductor photodiode can detect a photon with a maximum wavelength of 400 $\mathrm{n}\mathrm{m}$   , then its band gap energy is:

Planck's constant $h=6.63*{10}^{-34}$ J.s.

Speed of light $\mathrm{}\mathrm{c}=3*{10}^8\mathrm{m}/\mathrm{s}$  

The current flow through the resistance in the given circuit is : (Cut-off voltage for both diodes is 0.7 V)

A n-p-n transistor can be used as

The output (X) of the logic circuit shown in figure will be

 

In the above diagram, balance length for E' is ℓ₀. If cross sectional area of wire AB is doubled then what will be new balancing length ?

The figure shows a logic circuit with two inputs A and B and an output C. The voltage wave forms of A, B and C are as given, then logic circuit will be equivalent to :-