Experiement 6

Objectives: 1. To know the operations of the oscilloscope, digital multimeter, & function generator. 2. To know how to generate and explore different waveforms with specific amplitude & frequency. 3. To display the waves by the oscilloscope and measure their amplitude, frequency, & period. 4. To feel the main difference between the DC & AC measurement. Equipment: 5. Function generator.

6. Wires. 7. Digital multi-meter. 8. Oscilloscope. 9. Scope probes. Contents: 1. 2. 3. 4.

Oscilloscope. Function generator. Digital multi-meter. Generating & measuring the sinusoidal waveform.

Theory: 1. We have been familiar with the oscilloscope operations like the position of the signal & the voltage scale & the time scale for every square, and we can input two waves in the same time. 2. As we see in the figure 6.1 the sinusoidal signal has an amplitude (A) & period (T) so the frequency of this signal is f = 1/T. 3. we have another concept which is the effective value or r.m.s value & it equals the peak value divided by which is 2 for the sinusoidal signal Veff = Vp*0.707 .

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For a square signal : Veff = (1/Tƒ .T v(t)2 dt).5= (1/Tƒ .T V2 dt).5= (1/T T v2tT] dt).5= Calculation & data analysis: Measured quantity Input frequency (HZ) Period (ms) Calculated frequency (HZ) 1000 1 1000 2000 0.48 2083 3000 0.32 3125 4000 0.25 4000 5000 0.2 5000 Table 6.1 f = 1/T f1 = 1/0.001 = 1000 HZ f2 = 1/0.00048 = 2083 HZ f3 = 1/0.00032 = 3125 HZ f4 = 1/0.00025 = 4000 HZ f5 = 1/0.0002 = 5000 HZ We set the generator to generate a sinusoidal wave with effective value measured by the DMM as we want & with frequency 1000HZ & then measured the peak value with the oscilloscope & fill the table 6.2 Measured quantity Effective value (v) 1 2 3 4

Peak value (Vp)

Peak to peak value (V)

Average value (V)

1.4 2.8 4.2 5.6

2.8 5.6 8.4 11.2

0 0 0 0

2

Calculated effective value (V) 0.98 1.98 2.96 3.96

5 Table 6.2 Vpp = 2*Vp

6.8

13.6

0

4.8

Veff = Vp *0.707 Veff = 1.4*0.707 = 0.98v Veff = 2.8*0.707 = 1.98v Veff = 4.2*0.707 = 2.96v Veff = 5.6*0.707 = 3.96v Veff = 6.8*0.707 = 4.8v

Conclusions: 1. We can use the oscilloscope to measure the freaquency of the input signal & its amplitude. 2. We can measure the effective value of the signal by the digital multi-meter. 3. We see that the effective value of the signal Veff = VP*0.707 only used for the pure sinusoidal signal & it's different from one signal to another.

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