Basic Electrical Measurement

Aim

To learn how to use a digital multimeter and oscilloscope confidently and to use this skill to measure both AC and DC voltage and current as well as resistance, capacitance, time, frequency and phase.

Main Body

Resistance and DC voltage source measurements (1-8)

Description

Resistance of various resistors were measured and the current-voltage relationship of voltage sources with and without an internal resistance investigated.

Methods

The multimeter was used to both measure the resistance of different resistors and voltage across the simulated voltage source. Please refer to hand out for additional details. No difficulties were encountered nor changes made. However, if the experiment were done again, the same set of equipment would be used – two different sets were used in this case as the identity of the first set was never recorded. Additionally, the resistance of the resistors would only have been measured once as oppose to three times as the difference between each trial was negligible.

Observations

Though not necessarily relevant to the experiment, the sparks caused by short-circuiting was interesting.

Results and Calculations

Resistance Measurements

Resistor Nominal Resistance (Ω) Measured Resistance (Ω)

a 1000 1000

b 100 102.1

c 1M 1.017M

d 10M 10.56M

1 270 270.4

2 680 676

3 1.5k 1507

4 3.9k 3.89k

5 1M 1.025M

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Ideal DC Voltage Source Measurements

Resistor Resistance (Ω) Voltage Output _V0 (V) Current Output _I0 (A)

1 270.4 10 3.70e-02

2 676 10 1.48e-02

3 1507 10 6.64e-03

4 3.89e03 10 2.57e-03

5 1.025e06 10 9.76e-06

Example Calculation for Resistor 1:

I = V/R => I = 10/270.4 = 3.70e-02 (3s.f)

DC Voltage Source with Internal Resistance Measurements

Resistor Resistance (Ω) Voltage Output _V0 (V) Current Output _I0 (A)

1 270.4 2.104 7.78e-03

2 676 4.03 5.96e-03

3 1507 6.01 3.99e-03

4 3.89e03 7.95 2.04e-03

5 1.025e06 9.99 9.75e-06

Example Calculation for...