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- Question
A liquid has N permanent dipoles ?p per unit volume and has been subjected to dc field for a long time such that orientation polarization is P0. At t = 0, the field is suddenly removed, then polarization
Options- A. will remain constant at P0
- B. will become zero at t = 0
- C. will delay to zero with a time constant
- D. either b or c
- Correct Answer
- will delay to zero with a time constant
- 1. If the frequency is less than the damped frequency in a series- inverter
Options- A. the distortion of output voltage waveform is low
- B. the distortion of output voltage waveform is high
- C. the distortion of output voltage may be high or low depending on the load impedance
- D. none of the above Discuss
- 2. In a series inverter
Options- A. the commutating elements L and C are in parallel
- B. the commutating elements L and C are in series with load
- C. the commutating L and C may be in series or parallel with the load
- D. none of the above Discuss
- 3. In a fully controlled bridge converter feeding a resistive load the waveshapes of output voltage and output current
Options- A. are always similar
- B. can never be similar
- C. may be similar or dissimilar
- D. are similar only if a = 0 Discuss
- 4. A 200 turn coil has a self inductance of 10 mH. If the number of turns is doubled, all other quantities remaining the same, the self inductance will be
Options- A. 2.5 mH
- B. 5 mH
- C. 20 mH
- D. 40 mH Discuss
- 5. A fully controlled bridge converter is feeding an RLE load. For some circuit conditions firing angle is 47°. If connections of battery are reversed, the firing angle is likely to be
Options- A. 47°
- B. less than 47°
- C. more than 47°
- D. either more or less than 47° Discuss
- 6. A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls find cut off wavelength for dominant mode.
Options- A. 4 cm
- B. 1 cm
- C. 2 cm
- D. 8 cm Discuss
- 7. Half bridge and full bridge inverters of one type use different commutation methods.
Options- A. True
- B. False Discuss
- 8. A colour television signal having bandwidth of 4.6 MHz is digitised using 10 bits sample. The digital bit rate used for its transmission with PCM would be __________ kilobits/second.
Options- A. 92000
- B. 920
- C. 23000
- D. 230 Discuss
- 9. The snubber circuit consists of
Options- A. a capacitor connected in series with thyristor
- B. a capacitor connected in parallel with thyristor
- C. a resistor and capacitor in series connected across thyristor
- D. none of the above Discuss
- 10. When a single phase dual converter is operating in circulating current mode
Options- A. both converters are working as rectifiers simultaneously
- B. one converter is always working as rectifier and the other as inverter
- C. only one converter is working at one time
- D. both converters are either working as rectifiers or as inverters simultaneously Discuss
More questions
Correct Answer: the distortion of output voltage waveform is high
Correct Answer: the commutating elements L and C are in series with load
Correct Answer: are always similar
Explanation:
For resistive load output current is always proportional to output voltage.
Correct Answer: 40 mH
Explanation:
Inductance is proportional to square of number of turns.
Correct Answer: more than 47°
Correct Answer: 4 cm
Explanation:
.
Correct Answer: False
Correct Answer: 92000
Correct Answer: a resistor and capacitor in series connected across thyristor
Correct Answer: one converter is always working as rectifier and the other as inverter
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