Electric Circuits Answers

Question

The output characteristics of a transistor in common-emitter configuration can be regarded as straight lines connecting the following points

   IB =     20 µA        50 µA          80 µA       

VCE(V) 1.0 8.0 1.0 8.0 1.0 8.0

IC (mA) 1.2 1.4 3.4 4.2 6.1 8.1

Plot the characteristics and superimpose the load line for a 1 kΩ load, given that the supply voltage is 9V and the d.c. base bias is 50 μA. The signal input resistance is 800 Ω. When a peak input current of 30 μA varies sinusoidally about a mean bias of 50 μA, determine

(a) The quiescent collector current 

(b) The current gain 

(c) The voltage gain

(d) The power gain

1. ssuming that an oscilloscope displays a V_max of 5.22V and V_min of 1.33V. Calculate the percentage of modulation. (5 points)
2. Three (3) AM broadcast stations are spaced at 18 kHz, beginning at 73 kHz. Each station is allowed to transmit modulating up to 6 kHz. Compute for the upper and lower sidebands of each station and plot it in the frequency domain. (15 points)
3. Given a V_max of 7.45V and a modulation index of 0.691, calculate for V_min. (5 points)
4. A station is given a carrier frequency of 88 kHz. Having a modulating frequency of 12 kHz, compute for the upper and lower sidebands of the station. (5 points)

define Flux density ?

A moving coil instrument have a resistance of 25ohms gives full scale deflection when a current of 20mA is passed through it..Calculate the values of resistance required to enable the instrument to be used as (I) 0-10A ammeter (ii) 0-100v voltmeter

If q₁=-8.2C and q₂=4.9C, what is the electric potential difference V_a-V_b (in gigavolts GV)?

Three (3) AM broadcast stations are spaced at 18 kHz, beginning at 73 kHz. Each station is allowed to transmit modulating up to 6 kHz. Compute for the upper and lower sidebands of each station and plot it in the frequency domain.

Three resistors of 6-ohm resistance are connected in delta. Inside the delta, another 6-ohm resistor  is connected in wye. Find the resistance between any two corners. 

1. Given a dc bias of 0.5mA and a bandwidth of 10 kHz, calculate for the noise current.