Find VAB from the circuit if all the resistances are of same value of 1 Ω.
Redraw the Fig. 20(a), we have
The resistance P and Q are in Series, the equivalent resistance R1=1+1=2Ω
The resistance R1 and R are in parallel. The equivalent resistance R2=(2×1)/(2+1)=2/3 Ω
Similarly the resistance U and T are in series and equivalent resistance R3=1+1=2 Ω.
The resistance R2 and s are in series and equivalent resistance R4=2/3+1=5/3 Ω. Finally the resistance R3 and R4 are in parallel each other. Hence total resistance between terminal A and B is
Hence VAB=1×10/11=10/11 Amp.
Deduce the expression of torgue of electrodynamometer type instrument. Why multiplier is used with PMMC instrument? What do you mean by sensitivity of PMMC instrument? Why sensitivity of electrodynamometer type instrument is low? Why the scale of moving iron instrument is cramped at lower end?
With the neat sketch, explain working principle of a two – hole directional coupler. Derive the scattering matrix of magic Tee. A multi hole directional coupler is fed with single power of 2.8 mW at 10 GHz. The coupling factor is 3 dB and the directivity is better than 40 dB over X-band range. Find the distribution of power at all other ports.