What’s Your Temperature in Volts?
Experiment #1: Use the IC temperature sensor to make the following measurements. Be sure the sensor is set up correctly and that the temperature is stabilized in each environment for at least 10 to 15 seconds before recording the data.
Materials:IC temperature sensors; voltmeter; 3 beakers, one each of ice-water slush, warm water, and hot water; a oC alcohol thermometer
Make Measurements
Measure the Palm of Your hand
Each person in your group should make the following measurement and record the value below.
Measure the temperature of the palm of your hand with the IC sensor by placing the tip of the sensor in the center of your palm and wrapping your fingers tightly around it to make a fist. Let the sensor stabilize to a single reading. Then wait 10 to 15 seconds. Be patient!
The recorded voltage value from the palm of my hand is ______V.
Measure the Ice –Water Slush
In your group, measure the temperature of the ice-water slush with the glass thermometer. Let the thermometer stabilize for 10 to 15 seconds.
The temperature is ˚C.
In your group, measure the temperature of the ice-water slush with the IC sensor. Let the sensor stabilize for 10 to 15 seconds.
The recorded voltage value from the ice-water slush is ______V.
Record the data
In your group, use the glass thermometer and IC sensor to make measurements. Complete the table below.
Temperature Data for the IC Sensor and Celsius Thermometer
Item Measured / Reading from IC in Volts(x) / Reading from Thermometer in ˚C
(y)
ice–water slush / V / ˚C
water (room temperature) / V / ˚C
water (above room temperature) / V / ˚C
Graph the Data by Hand
After you have recorded the ordered pairs (x, y) (Volts, ˚C), for each item in the table, draw and label a coordinate grid. On the grid paper, write “IC Sensor: Voltage (V) vs. Temperature (˚C)” in ink. Finally, plot the ordered pairs on the coordinate grid.
Describe the relationship shown for this set of data, Volts versus oC, for the IC sensor.
Model the Data with an Equation
1. Draw a “best-fit line” for the data with ink. (A “best-fit line” can be described as a line that comes as close as possible to all the data points.)
2. Select two points on the best-fit line. Use the coordinates of the points to find the slope of the line. (Don’t forget the units!)
m =mIC = ______0C/V
3. Next, write the equation for this line by substituting the slope, m, and a single point (x1, y1) into the point-slope formula below. Then solve the equation for y.
yIC = ____x + _____0C
Verify Your Equation:
Normal body temperature is usually about 37˚C. Use the yIC equation to find the temperature of the palm of your hand in degrees Celsius (˚C) from the (Volts) value that you recorded. Show your work below and provide the answer in the space.
The temperature of my palm in Celsius is: 0C
Graph the Data with a Calculator (TI–83)
Now use a calculator to find a regression equation for changing temperature from Volts to ˚C.
1. Turn the calculator on.
2. Clear out old data by doing the following:
a. [STAT] [4] [2nd] [1] [ENTER]
b. [STAT] [4] [2nd] [2] [ENTER]
c. [STAT] [4] [2nd] [3] [ENTER]
3. Clear out old equations. Press [y = ]. Use [CLEAR] to delete equations.
4. Set what will lists will be graphed and the type of graph using the following steps.
a. [2nd] [y = ] [1]
b. Make sure the cursor is flashing on (On). Arrow down.
c. For Type, make sure the cursor is flashing on the top left graph. Arrow down.
d. Make sure Xlist says L1. If not, clear it and hit [2nd] [1]. You should see L1 typed there. Push [ENTER].
e. Make sure the Ylist says L2. If not, clear it and enter L2 using the idea in d. Push [ENTER].
f. Make sure the first Mark type is flashing. Push [2nd] [MODE].
5. Now we have to set the window – the values of x and y that will show on the screen.
a. [WINDOW]
b. Set the following values: Use the negative key in the bottom row, not the minus key. Use [ENTER] to go from row to row.
Xmin = -1.5
Xmax = 1.5
Xscl = 0.10 (This is the scale for x. Many values are OK.)
Ymin = -10
Ymax = 50
Yscl = 10 (This is the scale for y.)
Wres = 1
Push [2nd] [MODE].
6. Enter the data from the table above. Use Volts for L1 andoC for L2. Do the following.
a. [STAT] [1]
b. You will see three lists labeled L1, L2, and L3. You can use the blue arrow keys to go between lists.
c. Enter Volt values in L1 going from top down. After you type each number hit [ENTER].
d. Enter the oC numbers in L2 going from top down.
e. [2nd] [MODE] gets you back to the main screen.
7. Find a linear regression for the data. Push [STAT]. Arrow to [CALC]. Push [4 (LinReg)] and [ENTER]. The calculator screen shows you the values for a and b in a linear equation of the form y = ax + b.
8. You can paste this equation into [y = ] using the following steps.
Push [y = ]. Push [VARS]. Push [5]. Arrow to [EQ] Pick [1].
9. Now push [GRAPH] to see the scatter plot and the linear equation found by the calculator.
Write the equation generated by the calculator.
yIC= _____x + _____
How does this equation compare to the equation for the best–fit line you drew?
PLEASE Test Your Equation
Use the calculator equation to translate 1.03V into degrees Celsius.
1.03V = ______oC