Your SlideShare is downloading.
×

- 1. Part 1 1- What is the input resistance of an ideal current-measuring DMM? 2- What is the input resistance of an ideal voltage-measuring DMM? 3- Under what conditions will the voltage burden or the input resistance of the DMM produce a significant error in current measurement? Part 2 Voltage Ratio in decibels (dB) = 20 log10 (V1/V2) 1- Express the following ratios in decibels (dB): i) V1/V2 =100 ii) V1/V2 = 0.1 2- Change these dB values to voltage ratios: i) -10dB ii) 3dB 3- A Function Generator has a specification that the variation in the output voltage with frequency will remain flat to within Solution 1 the input resistance of an ideal current-measuring DMM is 0 2
- 2. the input resistance of an ideal voltage-measuring DMM is infinite. 3 When resistance connected in series with DMM measuring current is low or when resistance connected in parallel with DMM measuring voltage is high error is produced. Part 2 1 Voltage Ratio in decibels (dB) = 20 log10 (V1/V2) V1/V2 =100 = 40 dB V1/V2 = 0.1 Â Â = -20 dB 2 -10dB V1/V2 = 0.31 3dB V1 / V2 = 1.414 (root 2 ) Part 3 Change in magnitude = 1.12 (1dB = 1.12) Percentage change = 12 %