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Find and sketch or graph the sample regression line of \(y\) and \(x\) and the given data as points on the same axes. $$\begin{array}{lllllll}\text { Voltage } \boldsymbol{x}[\mathrm{V}] & 40 & 40 & 80 & 80 & 110 & 110 \\ \hline \text { Current } y[\mathrm{A}] & 5.1 & 4.8 & 10.0 & 10.3 & 13.0 & 12.7\end{array}$$ Alse find the resistance \(R[\Omega]\) by Ohms' law \((\sec , 29).\)

Short Answer

Expert verified
The regression line is \(y = 0.2476 + 0.118x\). Resistance \(R\) is 8.47 \(\Omega\).

Step by step solution

01

Organize the Data

We have paired data points where Voltage \(x\) values are \([40, 40, 80, 80, 110, 110]\) and Current \(y\) values are \([5.1, 4.8, 10.0, 10.3, 13.0, 12.7]\). These points can be paired as (40, 5.1), (40, 4.8), (80, 10.0), (80, 10.3), (110, 13.0), and (110, 12.7).
02

Calculate the Means

Find the means of \(x\) and \(y\). For \(x\), we have \(\overline{x} = \frac{40+40+80+80+110+110}{6} = 76.67\) V. For \(y\), \(\overline{y} = \frac{5.1+4.8+10.0+10.3+13.0+12.7}{6} = 9.32\) A.
03

Compute the Slope (b)

Use the formula \(b = \frac{\sum ((x_i - \overline{x})(y_i - \overline{y}))}{\sum (x_i - \overline{x})^2}\). Calculate each component: \((x_i - \overline{x})\), \((y_i - \overline{y})\), \((x_i - \overline{x})(y_i - \overline{y})\), and \((x_i - \overline{x})^2\). Find \(b = 0.118\).
04

Calculate the Intercept (a)

Use the formula \(a = \overline{y} - b\overline{x}\). Substitute \(\overline{y} = 9.32\), \(b = 0.118\), and \(\overline{x} = 76.67\) to get \(a = 0.2476\) A.
05

Write the Regression Line Equation

The equation of the regression line is \(y = a + bx\), which simplifies to \(y = 0.2476 + 0.118x\).
06

Graph the Points and Regression Line

Plot the data points and graph the line \(y = 0.2476 + 0.118x\) on the same axis. The line should pass close to the points, showing the trend of increasing current with voltage.
07

Calculate the Resistance R

Ohm's Law states \(V = IR\), rearranging gives \(R = \frac{V}{I}\). Using the slope \(b = 0.118\), which represents \(\frac{1}{R}\), the resistance \(R = \frac{1}{b} = \frac{1}{0.118} = 8.47 \Omega\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Ohm's Law
Ohm's Law is a cornerstone of electrical engineering and states that the voltage across a conductor between two points is directly proportional to the current flowing through it, provided the temperature remains constant. It is mathematically expressed as \( V = IR \), where \( V \) is voltage, \( I \) is current, and \( R \) is resistance. This fundamental principle allows us to understand how electric circuits function and how different components interact.
By rearranging the formula to \( R = \frac{V}{I} \), we can calculate the resistance when given values for voltage and current. In our exercise, this relationship helps us determine the resistance from the slope of the linear regression line between current and voltage data. This slope provides insight into the proportional relationship described in Ohm's Law.
Understanding Ohm's Law is crucial, as it applies to nearly every scenario involving electricity, from small circuits to massive power grids, making it an essential tool for electrical engineers and physicists alike.
Slope and Intercept Calculation
Calculating the slope and intercept is a key process in forming a linear regression model. This model predicts a dependent variable (in our case, the current) from an independent variable (the voltage). The process involves several steps to ensure accurate results.
**Slope calculation** requires the formula \( b = \frac{\sum ((x_i - \overline{x})(y_i - \overline{y}))}{\sum (x_i - \overline{x})^2} \). Here, \( x_i \) and \( y_i \) are data points, while \( \overline{x} \) and \( \overline{y} \) are their respective means. The slope \( b \) quantifies how much \( y \) changes for a unit change in \( x \). This is directly related to Ohm's Law, where the slope of the voltage-current relationship equals the inverse of the resistance.
**Intercept calculation** follows with the formula \( a = \overline{y} - b\overline{x} \), determining where the regression line intersects the \( y \)-axis. In our regression line equation, \( y = 0.2476 + 0.118x \), the intercept is \( 0.2476 \). This point often provides meaningful insight into the relationship at \( x = 0 \), although it is not always practically relevant in scientific contexts like Ohm's Law.
Data Visualization
Data visualization plays a crucial role in understanding relationships between variables. By plotting data points and regression lines, complex data becomes easier to interpret. In this case, we graph the voltage-current data to visually represent the relationship.
**Plotting the Data Points:** This provides a clear picture of how each pair of voltage and current values correlate. By marking these points on a two-dimensional plane, we begin to identify patterns and correlations.
**Drawing the Regression Line:** Once we have our slope and intercept, we plot this line to show the general trend of the data. The equation \( y = 0.2476 + 0.118x \) is used to construct the line which should pass as closely as possible to all data points. This line offers a visual representation of the predictive relationship.
Visualizations enable observers to quickly grasp patterns, outliers, and insights which may be less obvious in raw data. For Ohm’s Law, seeing the regression line through data points helps confirm the law's proportional relationship visually, enhancing conceptual understanding. Whether for academic purposes or real-world scenarios, visualization makes complex information accessible and actionable.

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