Alternating Current vs Direct Current problems
- 1. If a voltmeter measures a sine wave as 500 mV, what would be its average value?
Options- A. 159.0 mV
- B. 318.5 mV
- C. 353.5 mV
- D. 451.0 mV Discuss
Correct Answer: 451.0 mV
Explanation:
Some AC Voltage Conversion:
Peak to rms: multiply peak by 0.707.
Peak to average: multiply peak by 0.637.
Rms to peak: multiply rms by 1.414.
Rms to average: multiply rms by 0.9.
Average to rms: multiply avg by 1.111.
Average to peak: multiply avg by 1.567.
Mostly voltmeter shows rms value. So, Vav = 0.9*Vrms
= 0.9*500.
= 450mV ~ [D] 451 mV.
- 2. AC effective voltage is named:
Options- A. average
- B. peak
- C. peak-to-peak
- D. root mean square Discuss
Correct Answer: root mean square
- 3. What is the name of a device that converts sound waves to electrical waves?
Options- A. an amplifier
- B. an antenna
- C. a filter
- D. a microphone Discuss
Correct Answer: a microphone
- 4. What is the average value of a 12 V peak wave?
Options- A. 3.82 V
- B. 4.24 V
- C. 7.64 V
- D. 9.42 V Discuss
Correct Answer: 7.64 V
- 5. If the frequency of a radio wave is increased, then its wavelength will:
Options- A. increase
- B. decrease
- C. remain the same
- D. cannot tell Discuss
Correct Answer: decrease
- 6. A triangle wave consists of repeating:
Options- A. positive ramps only
- B. negative ramps only
- C. positive and negative ramps of equal value
- D. positive and negative ramps of unequal value Discuss
Correct Answer: positive and negative ramps of equal value
- 7. One oscilloscope selector knob that allows the major and minor divisions of the graticule to be used to determine a waveform period is called a:
Options- A. focus control
- B. time/cm control
- C. intensity control
- D. volts/cm control Discuss
Correct Answer: time/cm control
- 8. What term expresses the frequency of a rectangular wave?
Options- A. Hz
- B. period
- C. PRF
- D. PRT Discuss
Correct Answer: PRF
- 9. One adjustable knob on the oscilloscope that allows the trace to be aligned with a reference graticule is called the:
Options- A. position control
- B. focus control
- C. intensity control
- D. volts/cm control Discuss
Correct Answer: position control
- 10. What is the peak value of a household appliance that uses a 230 V ac source?
Options- A. 163 V
- B. 230 V
- C. 325 V
- D. 480 V Discuss
Correct Answer: 325 V
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