Why is the use of ac voltage preferred over dc voltage?

Explain the principle on which the working of a potentiometre is based. Why is the use of a potentiometer preferred over that of a voltmeter for measurement of e.m.f. of a cell?

Answer the following Why is a mixture of helium and oxygen gas preferred over air for respiration during deep sea diving?

A Zener diode is fabricated by heavily doping both p and n-sides of the junction. Explain why? Briefly explain the use of Zener diode as a dc voltage regulator with the help of a circuit diagram.

What is the peak value of the voltage of a 220V ac line?

Why is molality preferred over molarity State Kohlrausch's law of independent migration.

When the frequency of the ac voltage applied to a series LCR circuit is gradually increased from a low value , the impedance of the circuit.

A parallel plate capacitor in series with a resistance of 100 Omega , an inductor of 20 mH and an AC voltage source of variable frequency shows resonance at a frequency of (1250)/pi Hz: If this capacitor is charged by a DC voltage, source to a voltage 25 V, what amount of charge will be stored in each plate of the capacitor ?