Optical Communication Dispersion Quiz

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What does dispersion primarily affect in optical communication systems?

The color spectrum of the transmitted light

The overall power consumption of the system

The modulation frequency used in transmission

The timing of the signal pulses (correct)

Which of the following is a technique used to mitigate dispersion effects?

Frequency modulation schemes

Dispersion compensating fibers (correct)

Signal amplification modules

Pulse shaping algorithms

How does dispersion impact maximum transmission distance?

It increases the signal strength over longer distances

It decreases the transmission capacity

It deteriorates signal quality over distance (correct)

It eliminates the need for compensation techniques

What is often sacrificed in order to reduce dispersion effects in optical systems?

Available bandwidth Signup and view all the answers

Why is managing dispersion crucial in optical communication systems?

To ensure reliable and efficient operation Signup and view all the answers

What is a significant advantage of squirrel cage rotors in induction motors?

Simplicity in construction Signup and view all the answers

Which of the following is a disadvantage of squirrel cage rotor motors?

Lower starting torque Signup and view all the answers

What phenomenon occurs due to an improper combination of rotor and stator slots?

Cogging and Crawling Signup and view all the answers

What is the purpose of designing the length of the air gap in induction motors?

To improve cooling efficiency Signup and view all the answers

What is the empirical formula for calculating air gap length in induction motors?

$l_g = 0.2 + 2vDL$ mm Signup and view all the answers

Which rotor type generally exhibits better starting torque?

Slip ring rotor Signup and view all the answers

What effect does a longer air gap have on the magnetizing current?

Increases magnetizing current Signup and view all the answers

What does the presence of odd harmonics in a rotating magnetic field generally cause in induction motors?

Crawling Signup and view all the answers

What is the primary purpose of connecting external resistances to slip rings at starting?

To increase starting torque Signup and view all the answers

What is the maximum allowed flux density in the rotor teeth?

1.5 Tesla Signup and view all the answers

What is a crucial consideration when determining the number of rotor slots?

It should not be equal to the number of stator slots Signup and view all the answers

How is the rotor current calculated in relation to stator current?

Ir = (Kws x Ss x Z's) / (Kwr x Sr x Z'r) Signup and view all the answers

What is the allowed range for current density in rotor conductors?

4 to 6 Amp/mm2 Signup and view all the answers

What determines the size of the rotor slot?

Conductor arrangement based on the stator Signup and view all the answers

What is the safety limit for the voltage between slip rings for medium voltage machines?

400 volts Signup and view all the answers

What should the area of one rotor tooth be calculated based on?

Tooth width and iron length Signup and view all the answers

What is used to limit the total copper loss in a rotor?

Calculating the rotor winding resistance Signup and view all the answers

What effect do the 5th and 7th harmonics have on the magnetic poles compared to the fundamental?

They produce five and seven times the number of poles of the fundamental, respectively. Signup and view all the answers

What is the effect of 7th harmonic on the speed of a three-phase induction motor?

It tends to run the motor at one seventh of its normal speed. Signup and view all the answers

What is the phenomenon called when a motor refuses to run due to improper rotor and stator slot numbers?

Cogging Signup and view all the answers

How can the tendency of cogging be minimized?

By selecting proper rotor slots in relation to stator slots. Signup and view all the answers

What is one consequence of skewing rotor slots?

It increases leakage reactance. Signup and view all the answers

What guideline is used to avoid synchronous hooks in torque-speed characteristics?

Ss - Sr ? ±P, ±2P, ±5P Signup and view all the answers

What is the formula to determine the current per rotor bar in a squirrel cage induction motor?

Ib = (Kws x Ss x Z's) x I'r / (Kwr x Sr x Z'r) Signup and view all the answers

What type of rotor slots are generally preferred for better performance in induction motors?

Semi-closed or closed slots Signup and view all the answers

Which of the following is an effect of using fully closed rotor slots?

Reduced starting current Signup and view all the answers

What is the area of the end ring calculated from, considering the end ring current?

Area = Ie / de Signup and view all the answers

What is the calculated current in the rotor based on the given formula?

343.8 amps Signup and view all the answers

What is the standard conductor size selected for the rotor?

13 mm x 4.5 mm Signup and view all the answers

How is the rotor bar resistance calculated?

Resistance = resistivity x length / area Signup and view all the answers

What is the primary material used for stator windings?

Copper Signup and view all the answers

Which of the following best describes the purpose of rotor windings?

Induce current and create torque Signup and view all the answers

What technique is NOT typically used to measure stator winding resistance?

Slip-ring method Signup and view all the answers