1. NOCTI Review Lesson 2 Objectives: Compute values for voltage conversion (RMS, peak, ect). Calculate voltage and frequency on a oscilloscope.

2. RMS Values RMS, or effective, value stands for root-mean-square, is the square root of the mean of the square of the instantaneous currents.

3. RMS = peak x 0.707 Peak = RMS x 1.414

4. A sine wave has a peak value of 354 V. What is the RMS value?

5. RMS = peak x 0.707 RMS = 354 x 0.707 RMS = 250.3 V

6. An A.C. voltage of 325 pp has an effective value of what?

7. RMS = peak x 0.707 RMS = 162.5 x 0.707 RMS = 114.89 V

8. Oscilloscope operation The first thing to understand is that an oscilloscope is a voltmeter. It does not measure current, resistance, or watts.

9. The oscilloscope measures an amount of voltage during a period of time and produces a two-dimensional image.

10. The oscilloscope is divided into two main sections. One section is the voltage section, and the other is the time base for frequency.

11. Since the oscilloscope has the ability to measure voltage with respect to time, it is possible to compute the frequency of the wave form. Frequency F = 1 / T (time)

12. Oscilloscope Calculations The oscilloscope measures amplitude of voltage with respect to time.

13. The frequency of a wave form can be determined by dividing 1 by the time of one cycle. F = 1 / T F = Frequency in Hertz T = Time in seconds

14. A wave form shown on the display of an oscilloscope completes one cycle in 50 micro sec. What is the frequency of the wave form?

15. F = 1 / T F = 1 /.000050 F = 20,000 Hz

16. What is the peak-to-peak voltage of a waveform on a scope when the vertical height is set at.05v/divion and the total number of divisions of the waveform is 3.45 divisions.

17. Peak to Peak Voltage =.05v/divion x 3.45 divisions 173 mV

18. What is the frequency of a waveform when the waveform is 2 ¼ divisions and the horizontal time period is set at 20us/division?

19. F = 1 / T F = 1 / 2.25 x.000020 F = 1 /.000045 F = 22,222 Hz