Alternating Current

Which one of the following is correct?

• $V_0=1.414V_rms$

• $I_rms=1.414I_0$

• $V_0=10.70V_rms$

• $bothAandB.$

An A.C. voltmeter reads 250 volts. The frequency of alternating is 50 Hz, the peak value of voltage is

• 3525.0 volts

• 35.35 volts

• 353.5 volts

• 3.535 volts

If frequency of rotating coil of an A.C. generator is f Hz then frequency of e.m.f. produced in Pakistan is:

• 50 Hz

• 60 Hz

• f Hz

• None of these

A 100  $μF$     capacitor with 12V battery in series having frequency 50Hz the capacitive reactance will be

• 75Ω

•  16Ω     

• 40Ω

• 32Ω

An A.C series circuit having resistance 4Ω and 3Ω inductive reactance. The impedance will be

• 12Ω

• 7Ω

• 17Ω

• 5Ω

When A.C. pass through an inductor, voltage leads the current by:

• Half cycle

• Quarter cycle

• Full cycle

• None of these

In a R-C series circuit, current ______ applied voltage by   $\theta$   =

•  $Lead,\tan-11/ωCR$  

•  $Lead,π/2$  

•  $Lags,\tan-11/ωCR$  

•  $Lags,π/2$  

 The phase angle   $\theta$  in an R.L series circuit is expressed as:

•  $θ=\tan-1(ωL/R)$  

•  $θ=\tan(ωL/R)$  

•  $θ=\tan-1(R/ωL)$  

•  $None\ ofthese$  

When electrons in the transmitting antenna vibrate 94000 times per second, they produce radio waves having frequency

• 9.4 kHz

• 940 kHz

• 94kHz

• None of these

In frequency modulation, the amplitude of carrier waves is:

• Increases

• Remains constant

• Decreases

• None of these