pHYSICS

Experiment 5

Aim of the Experiment

To observe sine wave, square wave, triangular wave and ramp waveforms on the C.R.O. and to measure amplitude and frequency of the waveforms.

Principle

C.R.O. (Cathode Ray Oscilloscope) is the instrument which is used to observe signal waveforms. Signals a red is played in time domain i.e. variation in amplitude of the signal with respect to time is plotted on the CRO screen . X-axis represents time and Y-axis repr es en ts amplitude. It is used to measure amplitude, frequency and phase of the waveforms. It is also used to observe the shape of the waveform . C.R.O. is useful for troubleshooting purpose. It helps us to find gain of amplifier, test oscillator circuits. We can measure amplitude and frequency of the waveforms at the different test points in our circuit. Thus, it helps u s for fault finding procedures. In dual channel C.R.O. X-Y mode is available which is used to create Lissajous patterns. Latest digital storage oscilloscope display voltage and frequency directly on the LCD and does not require any calculations. It can also store waveform for further analysis. In this practical, we will measure amplitude and frequency of the different waveforms like sine wave, square wave, triangular wave and ramp wave.

Materials required

CRO, connecting wires, function generator

Procedure

1. Connect function generator output at the input of C.R.O. at channel 1 or at channel 2

2. Select proper channel i.e. if signal is connected to channel 1 select CH1 and if signal is connected to channel 2 select CH2

3. Adjust Time / Div knob to get sufficient time period displacement of the wave on the CRO screen .

4. With fin e tu n in g of time/ Div make the waveform steady on screen .

5. Use triggering controls if waveform is not stable

6. Keep volt/ div knob such that waveform is visible on the screen without clipping

7. Measure P-P reading along the y-axis. This reading multiplied with volt/ div gives peak to peak amplitude of the ac i/ p wave.

8. Measure horizontal division of one complete cycle. This division multiplied by time/ div gives a time period of the i/ p wave.

9. Calculate frequency using formula f = 1/ T.

10. Note down your readings in the observation table.

Observation Table

Calculation

Result

Reference Material

1. University Physics, F. W. Sears, M. W. Zemansky and H. D. Young. 13/e, 1986, Addison-Wesley

2. Virtual Lab (https://vlab.amrita.edu/index.php?sub=1&brch=280&sim=194&cnt=1)

Questions

1. What is the use of C.R.O. ?

2. What do you mean by dual channel C.R.O. ?