UNIT - I Short Question and Answers

Linear wave shaping

**1.Define linear wave shaping.**

Ans: The process which by the wave form of a non-sinusoidal signal is altered by transmitting the signal through a linear network is termed as **linear wave shaping.**

**2. Define linear network.**

**Ans:** A network comprising of linear elements is called linear network.

**3.What are the linear elements and why they called as linear elements.**

**Ans**: Resistor, capacitor and inductor are linear elements since the current passing through them is proportional to the voltage i.e. there is linear relation between the applied voltage and resulting current.

**4.Define time constant of RC circuit.**

**Ans: **Time constant of the RC circuit is the time required for the output voltage (voltage across the capacitor) to attain 63.2% of the final steady value.

**5. When the capacitor voltage becomes equal to the steady state value.**

**Ans:**After 5 time constants, the capacitor voltage becomes equal to steady state value (99.3% of V)

**6. why the high pass RC circuit called as RC differntiator.**

Ans: At RC<<T the high pass RC output is proportional to the time derivative of the input,hence it is called RC differentiator. This circuit finds useful application in converting a triangular wave into square wave.

**7.How to minimize the distortion in RC high pass RC circuit with pulse input.**

**Ans:**The time constant of the circuit must be very large as compared to the pulse width.

**8.Define %tilt of RC circuit.**

**Ans:**The decay in the amplitude of the output voltage wave due to the input voltage maintaining a constant level.

%Tilt =

X 100

**9.Write the relation between f _{1} and %tilt.**

Ans: %tilt= (p/f).f_{1 }X100

**10.Define rise time**

**Ans: **It is the time required for the voltage to rise from 10% to 90% of the steady state value is termed as rise time.

t_{r}= 2.2RC

**11. Write the relation between rise and bandwidth.**

Ans: t_{r}= 0.35/f_{2} or 0.35/Bandwidth

**12. Write the general solution which represents the response of RC circuit.**

Ans: V_{O}= V_{final} – (V_{final }– V_{intial})

**13.Define attenuator.**

**Ans: **Attenuator is the circuit that reduces the amplitude of the signal without leading to any distortion in the signal waveform. Example: CRO probe.

**14. Write the condition for perfect compensated attenuation**

Ans: R_{1}C_{1}=R_{2}C_{2}

**15.Write the time constant of RL circuit.**

Ans: t = L/R

**16. When the decaying exponential **

** reaches 36.8% of its initial value.**

Ans: After one time constant

**17. Write the damping constant of the RLC circuit.**

**Ans: **

**18.Define ringing circuit.**

Ans: The RLC circuit which gives nearly undamped oscilloscopes is generally referred to as Ringing circuit.

**19. Write the equation for cutoff frequencies of Low pass and High pass RL circuits.**

**Ans: ** Upper cut-off frequency f_{2}= 1/(2pL/R) -low pass RL circuit

Lower cut-off frequency f_{1}=1/(2pL/R)- High pass RL circuit