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1. Complete Table 1. (small) Trial Average Current, i Area V*s Total Charge, Q=a

ID: 3162190 • Letter: 1

Question

1. Complete Table 1. (small)

Trial

Average Current, i

Area V*s

Total Charge, Q=area/10000

Final Voltage, V

Capacitance, C1 = Q/V

1

-5.385E-4

239.89

0.023989

2.979275

8.05E-3

2

-5.385E-4

229.26

0.022926

2.984456

7.68E-3

3

-5.385E-4

183.26

0.018326

2.984456

6.14E-3

Average Capacitance

7.32E-3

Standard Deviation

0.001013

(2 points x 8 = 16 points)

2. Complete Table 2. (large)

Trial

Average Current, i

Area V*s

Total Charge,

Q=area/10000

Final Voltage, V

Capacitance, C2 = Q/V

1

-5.385E-4

523.86

0.052386

2.766839

0.01893

2

-5.385E-4

404.11

0.040411

2.792746

0.01447

3

-5.385E-4

347.28

0.034728

2.797927

0.01241

Average Capacitance

0.01527

Standard Deviation

0.00333

(2 points x 8 = 16 points)

3. Complete Table 3.

Configuration

Average Current, i

Area V*s

Total Charge,

Q=area/10000

Final Voltage, V

Capacitance, Ceff = Q/V

Parallel

-5.385E-4

456.43

0.045643

2.792746

0.01634

Series

-5.385E-4

188.74

0.018874

2.979275

0.00634

(2 points x 4 = 8 points)

a. Using the relation for parallel capacitors, Ceff = C1 + C2, calculate the effective capacitance of C1 and C2 in parallel with uncertainty based on data in Table 1 and 2. Statistically compare this effective capacitance to that measured in Table 3, comment as necessary. Show all work. (30 points)

b. Using the relation for series capacitors, 1/Ceff = 1/C1 + 1/C2, calculate the effective capacitance of C1 and C2 in series with uncertainty based on data in Table 1 and 2. Statistically compare this effective capacitance to that measured in Table 3, comment as necessary. Show all work. (30 points)

Trial

Average Current, i

Area V*s

Total Charge, Q=area/10000

Final Voltage, V

Capacitance, C1 = Q/V

1

-5.385E-4

239.89

0.023989

2.979275

8.05E-3

2

-5.385E-4

229.26

0.022926

2.984456

7.68E-3

3

-5.385E-4

183.26

0.018326

2.984456

6.14E-3

Average Capacitance

7.32E-3

Standard Deviation

0.001013

Explanation / Answer

standared deviation C1 = 0.001013

                                  C2 = 0.00333

C1 = 7.32e-3 +/- 0.001013

C2 = 15.27 +/- 0.00333

when C1 and C2 are in parallel

Ceff = C1 + C2 = 7.32e-3 +15.27e-3 +/- (0.001013 +0.00333)

    Uncertainity in sum or difference adds up, hence

Ceff = 22.59e-3 +/- 0.004343

           lower limit = 18.153e-3 , upper limit = 26.933 e-3

measured value = 0.01634 = 16.34e-3 is outside the expected range

b) when C1 and C2 are in series

Ceff = 1/[1/C1 + 1/C2] = C1C2/(C1 + C2) = 7.32e-3 *15.27e-3 /22.59e-3

                                      = 4.95e-3

for a quotient fractional uncertinities add up

fractional uncertainity Ceff = (1.013/7.73) + (3.33/15.27) + (4.343/22.59)

                                           = 0.5487

uncertainity = 0.5487 * 4.95e-3 = 2.72e-3

measured value = 6.34e-3

expected value 4.95 +/- 2.72e-3

measured value is within the range of expected value.