1. Introduction:

Theory:  The voltage measured across a load follows the Ohm's law which says that the current passing through a conductor between two points is directly proportional to the potential difference across the two points.

V α I   => V = I.R   (where R is proportionality constant)

R is known as resistance and it changes with material and temperature of conductor

Material Required: Oscilloscope, frequency generator, connecting wires, resistor, multimeter.

Description and Aim: To measure voltage using an oscilloscope and determine current and impedance by using Ohm's law.

For this exercise, the voltage drop across the resistance is measured. The measured voltage value is divided by resistance value to get the value of current.

I = V / R

2. Method:

Step 1) First, pick the resistor and place it on the circuit board. It is connected in series with the other circuit. To ensure that R2 and L2 does not short, the two scope probes and the ADD-INVERT method are used.

Step 2) Connect the channel 1 input to the side of the component with the greatest potential. The channel 2 input is connected to the other side. Connect ground clips on the oscilloscope probes to the common port of generator (black lead).

Step3) Invert channel 2 and switch vertical mode to ADD. The display on the oscilloscope shows the voltage drop across the component.

Step 4) Use oscilloscope to measure peak-to-peak voltage across R2, and calculate the total circuit current (I).

Step 5) Replace the two post connector across sensing resistor R2. Now use Add-Invert method to measure voltage drop across R1.

Step 6) Connect Channel 1 probe to left side of R1, and channel 2 probe to other side of R1.

Step 7) Set both channel vertical input attenuators to display 2.0 V/div. Select channel 2 INVERT function on the oscilloscope. Set vertical mode to ADD. Measure Vpk-pk across R1.

3. Results: (please correct them)

V = IR

I = V / R

I = V₂/R₂   = 200/ 10 = 20 mA (pk-pk)

4. Discussion:

Using the INVERT-ADD mode of oscilloscope measurement of current is done. Concept is measuring the maximum potential difference across the series path and subtracting the potential difference due to second resistance. Using current and potential difference we can find unknown impedance. Since resistance doesn't introduce any phase difference between current and voltage across it, this way is easier way to compute an accurate resistance value.

Posted Date: 3/2/2013 12:54:22 AM | Location : United States

Ask an Expert

Related Discussions:- Measuring with an oscilloscope, Assignment Help, Ask Question on Measuring with an oscilloscope, Get Answer, Expert's Help, Measuring with an oscilloscope Discussions

Write discussion on Measuring with an oscilloscope
Your posts are moderated

Write your message here..

Related Questions

Define the baud rate with respect to serial communication, With respect to ... With respect to serial communication define the baud rate. The rate of data transfer into serial data communication is denoted in bps. Bits per second (bps) are the rate of in

Determine harmonic factor hf of the input current, Q. Consider a full-wave ... Q. Consider a full-wave single-phase bridge recti?er circuit with dc motor load, as shown in Figure (a). Let the transformer turns ratio be unity. Let the load be such that the

Explain the operation of oscillators, Q. Explain the operation of oscillato... Q. Explain the operation of oscillators. Oscillator is a circuit that changes dc energy from the power supply into ac energy. An amplifier provided with a positive feedback bec

Find the ratio of the speed of the generator, Q. A dc shunt machine has an ... Q. A dc shunt machine has an armature winding resistance of 0.12  and a shunt-?eld winding resistance of 50 . The machine may be run on 250-V mains as either a generator or a mot

Basic componets., components and uses. components and uses.

Device switching losses and snubbers, May I know if your site can help me w... May I know if your site can help me with design a snubber and model the circuit using LTSpice software?

Explain dielectric current, Dielectric: Insulator that is used among th... Dielectric: Insulator that is used among the two plates of a capacitance is called as dielectric.  Electric field exists in the dielectric and the flux density depends on th

Show transformer equivalent circuits, Q. Show Transformer equivalent circui... Q. Show Transformer equivalent circuits? Transformers come in various sizes, from very small, weighing only a few ounces, to very large, weighing hundreds of tons. The ratings

Light triggering - power semiconductor devices , Light Triggering Whe... Light Triggering When  light is  thrown  on silicon the hole electron pair get excited an increases hence  the leakage  current of J 2   increases which  will increase I C1 a

Show how a 16-to-1 multiplexer implement the logic function, Q. Show how a ... Q. Show how a 16-to-1 multiplexer can be used to implement the logic function described by the following truth table.