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Questions and Answers
What is the relationship between voltage and current in a purely ohmic circuit?
What is the relationship between voltage and current in a purely ohmic circuit?
What is the maximum current 'I_m' in terms of the maximum voltage 'V_m' and resistance 'R'?
What is the maximum current 'I_m' in terms of the maximum voltage 'V_m' and resistance 'R'?
What does the equation $v = iR$ represent in an alternating current circuit?
What does the equation $v = iR$ represent in an alternating current circuit?
At what point does the instantaneous current ‘i’ reach its maximum value?
At what point does the instantaneous current ‘i’ reach its maximum value?
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Which of the following is NOT true about the alternating voltage and current waveforms in an ohmic resistor?
Which of the following is NOT true about the alternating voltage and current waveforms in an ohmic resistor?
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Study Notes
A.C. Through Pure Ohmic Resistance
- The applied voltage is given by the equation: v = Vm sin ωt
- Let R be the ohmic resistance, and i be the instantaneous current.
- For equilibrium, the applied voltage must supply the ohmic voltage drop only, so v = iR
- Substituting v into the equation, we get Vm sin ωt = iR. This gives us i = Vm sin ωt / R.
- The current 'i' is maximum when sin ωt is unity. The maximum current (Im) is Vm / R.
- Therefore, the current equation becomes i = Im sin ωt
- Comparing the equations for voltage and current, we find voltage and current are in phase.
- This is shown graphically in the figure. The voltage and current waveforms are directly aligned.
- This is also illustrated vectorially in the figure, where the voltage vector (VR) and the current vector (I) are aligned (in phase).
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Description
This quiz explores the relationship between voltage and current in an AC circuit through pure ohmic resistance. It covers key equations and concepts, including maximum current, phase alignment, and the graphical representation of voltage and current waveforms. Test your understanding of how these components interact in an AC circuit.