Question

Q.N. 1:-

Identify the correct equation that describe the relationship between a sine and cosine wave.

		a. v(t) = A sin (2πft + π/2) = A cos (2πft)
		b. v(t) = A sin (2πft) = A cos (2πft + π/2)
		c. v(t) = A sin (2πft ) = A cos (2πft)
		d. v(t) = A sin (2πft - π/2) = A cos (2πft)

Q.N. 2:-

What is true about a connectionless packet switched?

		a. each datagram must contain both source and destination addresses
		b. without a connection, datagrams may not arrive in sequential order at the destination
		c. establishment of a connection between communicating points is not required prior to exchanging datagrams, thus reducing overhead communications
		d. all of the above are true

Q.N. 3:-

A multiplexer is a device that combines multiple frequency channels or time slots together to create an aggregate output.

True

False

Q.N. 4:-

Convert 100 watt to decibels referenced to 1 milliwatt.

		a. 50 dBW
		b. 50 dBm
		c. 130 dBm
		d. 100E3 W

Answer 1

Q.No1:

a. v(t) = A sin (2πft+ π/2) = A cos (2πft)

sin(A+B)=sin A cos B +sin A cos B; sin pi/2)=1;cos(Pi/2)=0

sin (wt +π/2) =sin wt cos π/2 +sin π/2 cos wt = cos wt

A sin (2πft +π/2) = A cos (2πft) ----True

b. v(t) = A sin (2πft) = A cos (2πft + π/2) -False

cos(A+B)=cos A cos B- sin A sin B;

cos (wt + π/2) =coswt cos π/2- sin wt sin π/2;

= -sin wt = -sin(2pift)

c. v(t) = A sin (2πft ) = A cos (2πft) - False

d. A sin (2πft - π/2) = A cos (2πft)

sin(A-B)=sin A cos B- sin A cos B

sin (wt -π/2) =sin wt cos π/2 - sin π/2 cos wt = -cos wt

A sin (2πft - π/2) = A cos (2πft) --- False

Answer : (a)

Q.N0 2:

Answer (d)

Yes.Each datagram must contain both source and destination addresses.In connection less packet switching,datagrams may be out of order at the destination.

Q.N0 3:

True

Q.N0 4:

Pdbm = 10 X log (1000 *100) = 50dbm

Answer: (b)