Question

Choose the correct option about Alternating voltage –
A) It is independent of time
B) It varies directly with time
C) It varies inversely with time.
D) It varies with time.

Answer 1

Hint: Alternating voltage is the changing sinusoidal form of voltage which is the voltage in Alternating current. The voltage changes its polarity with time. The number of times the polarity changes depends on the frequency of the Alternating voltage.

Complete answer:
Alternating current involves the current flow in the form of a sinusoidal wave. It’s direction changes with time as the sine wave. Alternating voltage is the voltage involved in the alternating current. Since the current changes with the time the alternating current voltage should also change with time. Actually, it is the reverse. An alternating voltage introduces an alternating current in the circuit.
Let us consider the alternating form of voltage. The equation is given by –
 \[V={{V}_{0}}\sin \omega t\]
Where, V is the voltage at an instant ‘t’, \[{{V}_{0}}\] is the maximum amplitude of voltage, \[\omega \] is the angular frequency and ‘t’ is the time.

From the equation we can conclude that the Voltage varies with time and is not directly proportional. It changes as a function of sine.
Therefore, Alternating Voltage varies as a function of time.

The correct answer is option D.

Note:
- The current lags or leads the voltage in phase with respect to the elements used in the circuit. A resistor only circuit does not show variation in phase between the voltage and current, whereas a inductor and capacitor circuit shows phase variations.
- The alternating current and alternating voltage are related to each other in various ways depending on the elements in the circuit.