Line Integral – Definition and Examples with Solutions

# Line Integral – Definition and Examples with Solutions

## What is a Line Integral?

A line integral is a calculation that determines the total length of a curve. The calculation is done by integrating the curve’s function along the curve.

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## Line Integral Definition

The line integral of a function is the sum of the products of the function’s value at each point in the line segment between two points and the length of the line segment.

## Line Integral of the Vector Field

The line integral of the vector field is a measure of the total amount of work done by the vector field as a vector moves along a curve. The line integral is computed by taking the integral of the vector field over the entire curve.

The line integral of a vector field is also called a path integral.

## Application of Line Integral

Let us consider a simple example of a line integral. Suppose we want to calculate the line integral of the function

along the curve

We can use the fundamental theorem of calculus to calculate this line integral. We know that the derivative of is , so the line integral can be written as

We can evaluate this line integral by integrating it over the curve . This gives

We can also write this line integral in terms of the variables and :

This line integral can be interpreted as the amount of fluid (in units of ) that flows through the curve in a given time interval .

## Step-by-Step Guide to solving Line Integrals

This is a step-by-step guide on how to find the line integral of a function

1. Identify the function and its derivatives

2. Choose a path along which to integrate

3. Evaluate the integral at each point on the path

4. Combine the results to find the line integral

## Difference between Line Integrals and Definite Integrals

The main difference between line integrals and definite integrals is that line integrals involve multiple integrals over a curve, while definite integrals involve a single integral over a given interval.

Another difference is that line integrals always yield a result in terms of a physical quantity, such as displacement, velocity, or energy, while definite integrals can yield a variety of results, depending on the function being integrated.

Finally, line integrals are more difficult to compute than definite integrals, because they require evaluating the integrals over the entire curve, whereas definite integrals can be evaluated by breaking the interval into smaller pieces and using the Fundamental Theorem of Calculus.

## Tips to understand Line Integrals:

1.Line integrals are used to calculate the work done in moving a charge along a path in a electric field or the flux of a vector field through a surface.

2.Line integrals are a way of calculating the accumulation of a vector field along a path.

3.Line integrals can be used to calculate the potential energy of a system.

4.Line integrals are a way of calculating the circulation of a vector field.

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