Chapter 12: Problem 43
Solve the given problems. The electric field intensity of a light wave can be described by \(12.4 \underline{/ 78.3^{\circ}} \mathrm{V} / \mathrm{m} .\) Write this in rectangular form.
Short Answer
Expert verified
The rectangular form is approximately \(2.57 + 12.11i\).
Step by step solution
01
Understanding Polar Coordinates
The polar form given is \(12.4 \, / \, 78.3^{\circ}\). This indicates a magnitude of 12.4 and an angle of 78.3 degrees. In polar coordinates, a point is defined by a distance from origin and an angle from the positive x-axis.
02
Converting to Rectangular Form
To convert from polar to rectangular form, use the formulas: \( x = r \cos \theta \) and \( y = r \sin \theta \), where \( r = 12.4 \) is the magnitude and \( \theta = 78.3^{\circ} \) is the angle.
03
Calculate the x-component
Use the formula \( x = 12.4 \cos(78.3^{\circ}) \). First, convert the angle to radians: \( \theta = 78.3^{\circ} = 78.3 \times \frac{\pi}{180} \approx 1.366 \text{ radians} \). Then calculate: \( x \approx 12.4 \cos(1.366) \) which gives approximately \( x \approx 2.57 \).
04
Calculate the y-component
Use the formula \( y = 12.4 \sin(78.3^{\circ}) \). With the same conversion, \( y \approx 12.4 \sin(1.366) \), resulting in approximately \( y \approx 12.11 \).
05
Final Rectangular Form
Combine the x and y components to express the rectangular form: \( 2.57 + 12.11i \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polar Coordinates
Polar coordinates provide a unique way to determine the position of a point in a plane. Unlike the familiar Cartesian (or rectangular) coordinates, which use an x and y coordinate, the polar system uses a radius and an angle. The radius, often denoted by \( r \), is the distance from a central reference point, usually called the origin, to the point itself. Meanwhile, the angle, \( \theta \), specifies the direction from the positive x-axis to the line connecting the origin and the point. The angle is typically measured in degrees or radians.
- Magnitude \( (r) \): Represents how far away the point is from the origin.
- Angle \( (\theta) \): Indicates the point's direction relative to the positive x-axis.
Rectangular Coordinates
Rectangular coordinates, or Cartesian coordinates, use two perpendicular axes typically labeled as x and y to locate a point in a plane. These axes intersect at a point known as the origin. Each point is represented as (x, y), with x denoting the horizontal distance and y the vertical distance from the origin.
The conversion from polar to rectangular coordinates involves two primary trigonometric functions: cosine and sine. By knowing the distance (magnitude \( r \)) from the origin and the angle \( \theta \), you can find the x and y components using the following formulas:
The conversion from polar to rectangular coordinates involves two primary trigonometric functions: cosine and sine. By knowing the distance (magnitude \( r \)) from the origin and the angle \( \theta \), you can find the x and y components using the following formulas:
- \( x = r \cos(\theta) \)
- \( y = r \sin(\theta) \)
Trigonometry
Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles. It plays a crucial role in polar to rectangular coordinate conversion. The cosine and sine functions, central to trigonometry, are used to find the corresponding x and y components for a given polar coordinate.
With an angle \( \theta \), cosine measures the adjacent over hypotenuse ratio in a right triangle, which corresponds to the x-component in a coordinate plane. Likewise, sine represents the opposite over hypotenuse ratio, aligning with the y-component. To work seamlessly with these trigonometric functions, angles must often be converted to radians from degrees, when necessary, as illustrated in conversion calculations such as \( 78.3^{\circ} = 1.366 \text{ radians} \).
With an angle \( \theta \), cosine measures the adjacent over hypotenuse ratio in a right triangle, which corresponds to the x-component in a coordinate plane. Likewise, sine represents the opposite over hypotenuse ratio, aligning with the y-component. To work seamlessly with these trigonometric functions, angles must often be converted to radians from degrees, when necessary, as illustrated in conversion calculations such as \( 78.3^{\circ} = 1.366 \text{ radians} \).
- Cosine \( (\cos) \) function: Determines the x-component
- Sine \( (\sin) \) function: Determines the y-component
- Radians and Degrees: Conversion necessary for precise calculations