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WAEC Physics 2020 Objective — Question 37

Question 37 of 50 from the West African Examinations Council (WAEC) Physics 2020 Objective paper, with the correct answer and a full explanation.

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In an electric circuit, an inductor of inductance 0.5 H and resistance 50 ohm is connected to an alternating current source of frequency 60 Hz. Calculate the impedance of the circuit.

  • A. 50.0 ohm
  • B. 150.5 ohm
  • C. 195.0 ohmCorrect
  • D. 1950.1 ohm

Explanation

Given L=0.5H, R=50 ohm, f=60Hz, required Z=? Z=sqrt(R^2+XL^2), where XL=2(pi)fL=2(pi)x60x0.5=188.52 ohm. Z=sqrt(50^2+188.52^2)=sqrt(2500+35,539.6)=sqrt(38039.79)=195.04 ohm.

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