Draw the output signals C₁ in the given combination of gates.

A student has to use an appropriate number of
(i) NAND gates (only) to get the output Y₁
(ii) NOR gates (only) to get the output Y₂
From two given inputs A and B as shown in the diagram.

Identify the 'equivalent gate' needed in each case.Show how one can connect an appropriate number of (i) NAND (ii) NOR gates respectively in the two cases to get these' equivalent gates'.

The graph of potential barrier versus width of depletion region for an unbiased diode is shown in A. In comparison to A, graphs B and C are obtained after biasing the diode in different ways. Identify the type of biasing in B & C and justify your answer.


Explain why:
LEDs are made of compound semiconductor and not by elemental semiconductors. 

Calculate the length of quarter wave antenna for transmission frequency of 20 MHz

Name the three different modes of propagation of electromagnetic waves.Explain using a proper diagram the made of propagation used in the frequency range from a few MHz to 40 MHz.

For an optical communication system, operating at \(\lambda =800\ nm\), only 1% of the optical source frequency is the available channel bandwidth. How many channels can be accomdated for transmitting video T.V. signal requiring an approximate bandwidth of 4.5 MHz?

Figure shows a communication system. Which is the output power when input signal is 1.01 mW? (Gain in dB=\(10\log { _{ 10 }\frac { { P }_{ 0 } }{ { P }_{ 1 } } } \))

Draw schematic diagram showing the (i) ground wave (ii) sky wave and (iii) space wave propagation modes for em waves.
Write the frequency range for each of the following:
(i) Standard AM broadcast
(ii) Television
(iii) Satellite communication

Explain with reason
(i) In amplitude modulation, the modulation index μ is kept less than or equal to 1.
(ii)  The maximum amplitude of an amplitude modulated wave is found to be 15V while its minimum amplitude is found to be 3 V. What is the modulation index?
(iii) Why amplitude modulated signal be noisier than a frequency modulated signal upon transmission through a channel?