/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 54 The current in a series \(R L\) ... [FREE SOLUTION] | 91Ó°ÊÓ

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The current in a series \(R L\) circuit rises to half its final value in \(7.6 \mathrm{s}\) What's the time constant?

Short Answer

Expert verified
The time constant of the RL circuit is \(10.9s\).

Step by step solution

01

Understanding the concept of Time constant

As we know, in an RL series circuit which consists of a resistor (R) and an inductor (L), the time constant is the time it takes for the current in the inductor to rise to \(1 - 1/e\) (about 63.2%) of its maximum value. This time constant is represented by \(Ï„ = L / R\), where L is the inductance and R is the resistance of the circuit.
02

Appropriating given information to the circuit's exponential growth

We are given that the current reaches half of its maximum value in 7.6 seconds. The time for the current to reach any fraction \(x\) of its maximum value in such a circuit is given by the formula \(t = -Ï„ * \ln{(1-x)}\), where \(\ln\) is the natural logarithm function.
03

Calculation of the Time constant

We can transform that equation and solve for the time constant \(Ï„\). The formula will then be: \(Ï„ = -t / \ln{(1-x)}\). We sub in \(t = 7.6s\) and \(x = 0.5\) (since the current reaches half of its final value) into our formula: \(Ï„ = -(7.6s) / \ln{(1-0.5)}\)
04

Complete the calculation

Perform the calculations which gives the result of \(Ï„ = 10.9s\).

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