AA Revision 3

The voltage of a pure sine wave is given by the equation 𝑣=10 sin 439.8t volts. What is the instantaneous voltage at 𝑡=0.012 seconds?

• A) - 8.44 volts
  

• B) -7.70volts
  

• C) 7.70 volts
  

• D) 8.44 volts

When an alternating voltage is applied to a purely resistive circuit of 10 Ω, a current of 5.37 A is recorded. What is the max instantaneous voltage supplied?

• 53.7 V

• 75.95 V

• 84.30 V

• 168.87 V

A 50 Ω resistor is subjected to an AC current with a peak value of 0.8A. What is the maximum instantaneous voltage across the resistor?

• A) 25 V
  

• B) 40 V
  

• C) 50 V
  

• D) 20 V

In an AC circuit, a 12 Ω resistor has a peak current of 6 𝐴6A. What is the maximum instantaneous voltage?

• A) 24 V
  

• B) 36 V
  

• C) 72 V
  

• D) 12 V

What is the reactance of an inductor which allows a 4 A current to flow when a 120 V, 60 Hz source is connected?

• 10 Ω

• 20 Ω

• 30 Ω

• 40 Ω

If the rms current in a resistor is 5 A, and the voltage across it is given by v = 14.14 sin ωt volts, determine the resistance of the resistor.

• 1 Ω

• 2 Ω

• 10 Ω

• 20 Ω

Calculate the capacitance of a capacitor whose reactance is 100 Ω at 60 Hz.

• 2.65 nF

• 26.5 nF

• 2.65 µF

• 26.5 µF

A pure inductance of 100mH is connected to a sinusoidal supply of 5 Vrms at a frequency of 51 Hz.

Calculate the inductive reactance of the inductor and the rms value of current in the circuit

• XL = 32.04 Ω

  𝐼𝑟ms = 0.157 𝐴

• XL = 3.204 Ω

  𝐼𝑟ms = 1.57 𝐴

• XL = 320.4 Ω

  𝐼𝑟ms = 15.7 𝐴

• XL = 3.204 KΩ

  𝐼𝑟ms = 157 𝐴