Answer Happy

Following Fig 7.6 and parts 1- 2, we get this square wave.  र 
This circuit setup corresponds to figure 7.7. We now have a capacitor in series with the resistor. The oscilloscope is now probing the capacitor. After following parts 4-7 for three different resistors, we get the following images on the oscilloscope. Compare these to Fig. 7.8.
Here is one charge cycle for the 5.1kΩ resistor. We can estimate Vo =3 vertical grids. That means 0.63Vo=1.9 girds. The horizontal grid value at which the line crosses the vertical value of 0.63Vo is approximately 0.6 grids, our value. That means if we want in terms of the time, we multiply it by time value for one horizontal grid M (converted to seconds). Therefore =0.6M=0.62.510−5sec =1.510−5 We record all of this in Table 7.1.
4. Take the first of your three capacitors and the 5.1kΩ resistor, and set up the circuit shown in Fig. 7.7. Choose the square wave on the function generator and set the frequency to 300 Hz. Connect the oscilloscope probe across the capacitor and press the AutoRange button to observe the waveform on the screen. 5. It might be necessary to change the frequency of the square wave. You are looking for charge and discharge patterns that show the voltage asymptotically approaching Vθ​ and 0 , respectively. If the duration of the square wave is too short, that is, its frequency is too high, then you should lower the frequency until the pattern looks similar to those in Figs. 7.8 and 7.9. Alternatively, you might also want to raise the frequency of the square wave. There is no one correct frequency of square wave to use, it just needs to be one that gives a sufficiently long period so that the charging capacitor's voltage can approach V0​.You may also change the time scale M of the oscilloscope using the Horizontal Scale button to "zoom" in on a single charge cycle. When changing the frequency of the function generator, you should verify that the amplitulle of the signal on the oscilloscope still extends over 6.3 grids (it probably will). If necessary, adjust the amplitude on the function generator with the Output Level knob. 6. Now that you have a nice looking charge cycle on the screen, adjust the Horizontal Position knob to move the bottom of the charge cycle over to the nearest grid line. This is illustrated in Fig. 7.1. Use your finger to go up four grid lines on the screen from the beginning of the charge cycle. Observe how far to the right you must move your finger to the right to get to the curve. It will probably be a part of a grid, such as 0.3,0.4, etc. Multiply this fraction by the value of M shown at the bottom of the screen. This product is τ, the time constant for the capacitor. 7. Record the resistor value, fractional number of grids that you moved horizontally, the value of M, and the value of τ in Table 7.1. 8. Change the resistor to a 10kΩ resistor and repeat the measurement of τ. Change the resistor to a 20kΩ resistor and repeat the measurement of τ. After recording the data in the data table, prepare a graph of the three τ values versus the three R values. Find the slope of the best-fitting straight line. The slope gives you the value of the capacitor.