Alternating CurrentMedium
Question
The peak value of an alternating current is 5 A and frequency is 60 Hz. How long will the current, starting from zero, take to reach the peak value?
Options
A.$\frac{1}{120}\text{ }s$
B.$\frac{1}{60}\text{ }s$
C.$\frac{1}{30}\text{ }s$
D.$\frac{1}{240}\text{ }s$
Solution
Sol. [Key Concept: AC current — time to reach peak from zero] Alternating current,
$$i = i_{\text{peak}\text{~}}sin(\omega t)$$
where $\omega = 2\pi f = 2\pi \times 60 = 120\pi rad/s$
$$\begin{matrix} & \ \Rightarrow \ i = 5sin(120\pi t) \\ & \ \Rightarrow \ 5 = 5sin(120\pi t) \end{matrix}$$
$$\Rightarrow \ sin(120\pi t) = 1 = sin\left( \frac{\pi}{2} \right)$$
$$\begin{matrix} & \ \therefore\ 120\pi t = \frac{\pi}{2} \\ & \ \Rightarrow \ t = \frac{1}{240}\text{ }s \end{matrix}$$
Create a free account to view solution
View Solution FreeMore Alternating Current Questions
An inductive reactance, XL = 100 W, a capacitive reactance, XC = 100 Ω, and a resistance R = 100 Ω are connect...In the given circuit the reading of voltmeter V1 and V2 are 300 volts each. The reading of the voltmeter V3 and ammeter ...In a purely capacitive circuit average power dissipated in the circuit is -...A broad metal plate is connected to earth through a conducting wire as shown. An electron flies with constant velocity a...The effective value of current i = 2 sin 100π t + 2 sin (100πt + 30o) is...