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Alternating current lead the applied e.m.f. by p/2 when the circuit consists of
  • a)
    only resistance
  • b)
    only capacitor
  • c)
    only an inductance coil
  • d)
    capacitor and resistance both
Correct answer is option 'B'. Can you explain this answer?
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Alternating current lead the applied e.m.f. by p/2 when the circuit co...
Explanation:

AC Circuit with Capacitor

When an AC circuit contains only a capacitor, the current leads the applied emf by p/2.

- In an AC circuit, the voltage across the capacitor changes with time.
- As the voltage across the capacitor changes, the capacitor charges and discharges.
- When the voltage across the capacitor is increasing, the current flowing through the capacitor is in the opposite direction of the voltage.
- When the voltage across the capacitor is decreasing, the current flowing through the capacitor is in the same direction as the voltage.
- Therefore, the current leads the voltage by p/2 in an AC circuit with only a capacitor.

Mathematical Explanation

- In an AC circuit with only a capacitor, the impedance of the capacitor is given by Zc = 1/jwc, where j is the imaginary unit, w is the angular frequency, and C is the capacitance.
- The current through the capacitor is given by Ic = V/Zc, where V is the applied emf.
- Substituting Zc, we get Ic = jwCV.
- The current leads the voltage by p/2, which means that the phase angle between the current and voltage is p/2 or 90 degrees.

Conclusion

Thus, we can conclude that in an AC circuit with only a capacitor, the current leads the applied emf by p/2 or 90 degrees.
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Alternating current lead the applied e.m.f. by p/2 when the circuit co...
Capacitor circuit current leads by voltage pi/2...inductor circuit voltage leads by current pi/2...
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Read the following text and answer the following questions on the basis of the same:Capacitor Colour Code: Capacitor values as written on small capacitors are sometimes misleading. Letters like p (pico) or n (nano) are used in place of the decimal point to identify its position and the value of the capacitor. For example, a capacitor labelled as n33 = 0.33nF, 8n2 = 8.2nF, 22n = 47nF and so on. Sometimes capacitors are marked with the capital letter K to signify a value of Kilo pico-Farads. As for example, a capacitor with the markings of 100K would be 1000 × 100 pF = 100 Kpf = 100 nF. Sometimes, a three letter code consists of the two value digits and a multiplier. For example, the digits 471 = 47 × 10 = 470 pF, 332 = 33 × 100 = 3300 pf. To reduce these confusions an International colour coding scheme was developed almost the same as that of resistance colour code.The value obtained from colour code is in pf.Two capacitors marked as 221 and 220 respectively are joined in parallel. What is the total capacitance value?

Alternating current lead the applied e.m.f. by p/2 when the circuit consists ofa)only resistanceb)only capacitorc)only an inductance coild)capacitor and resistance bothCorrect answer is option 'B'. Can you explain this answer?
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