### Chapter #8 :Waves and Sound : Short Q/A / C.R.Q's

Q. If a pendulum is vibrated at a deep well .What will be the effect on the Time Period?
Ans. As we know that g decreases with the depth.
g’=g (1-d/ Re 2)
and the time period of the pendulum is
T=2Ï€√ l/g
So according to the formula if the value of the g decreases the time period will increase
Then if a pendulum is vibrated at a deep well its time period will be grater than on earth.

Q. A wire hangs from a dark high tower so that the upper end is not visible. How can we determine the length of the wire?
Ans. First we tied a point mass with this string and then make it vibrate. The time period of this pendulum can be noticed. Now a/c to formula
L=gT/4 Ï€2
By knowing the value of g, the time period of vibration the length of wire can be calculated.

Q. Is it possible for two identical waves traveling in the same direction along a string to give rise to a stationary wave?
Ans. No . A standing wave, also known as a stationary wave, is a wave that remains in a constant position. This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions.

### COMMON COLLECTOR CONFIGURATION OF A TRANSISTOR

COMMON COLLECTOR CONNECTION

In  this  configuration  the  input  is  applied  between the  base  and  the  collector and  the  output  is  taken  from  the  collector  and  the  emitter.  Here  the  collector  is common to both the input and the output circuits as shown in Fig.

Common Collector Transistor Circuit

In  common  collector  configuration  the  input  current  is  the  base current  IB  and  the output current is the emitter current IE. The ratio of change in emitter current to the  change in the base current is called current amplification factor.

It is represented by

COMMON COLLECTOR CIRCUIT

A test  circuit  for determining the  static characteristic  of an NPN transistor is shown in Fig. In this circuit the collector is common to both the input and the output circuits.   To   measure   the   base   and   the   emitter   currents,   milli   ammeters   are connected in series with the base and the emitter circuits. Voltmeters are connected   across the input an…