( ) is not the index of power quality.
A: voltage
B: current
C: frequency
D: waveform
A: voltage
B: current
C: frequency
D: waveform
举一反三
- The<br/>common-base amplifier has _()()()__. A: voltage gain, current gain, and power gain B: voltage gain and power gain, but no current gain C: current gain and power gain, but no voltage gain D: current gain and voltage gain, but no power gain
- The function of direct current regulated power supply is to input an alternating current power of 220volts, so that it can output __________.( ) A: alternating current 200 volts voltage B: direct current 24 volts voltage C: direct current 200 volts voltage D: alternating current 24 volts voltage
- The voltage meter and current meter on the main switchboard shows ( <br/>). A: phase voltage and phase current of generator B: line voltage and line current of generator C: line voltage and line current of crane D: line voltage and line current of shore power
- For the generator control panel onboard a ship with AC electrical power network, it has voltage meter, current meter, and ( ) also. A: frequency<br/>meter, power meter, and power factor meter B: frequency<br/>meter, power meter and mega ohm meter C: frequency<br/>meter, power meter and rotating speed meter D: frequency<br/>meter, mega ohm meter and rotating speed meter
- The effective value of ac voltage or current is（ ） A: The average value of a voltage or current B: DC equal to the AC thermal effect is defined as the effective value of AC C: voltage or current are 0.707 of their amplitudes D: closely related to the frequency of alternating current