Tutorial 1b

INTRODUCTION OF MEASURENT AND INSTRUMENT

1) Given the expected voltage value across a resistor is 80V. The measurement is 79V.
Calculate,

i. The absolute error

ii. The % of error

iii. The relative accuracy

iv. The % of accuracy

(ANSWER)

i. Absolute error, e=1V

Ii. % error = 1.25%

Iii. Relative accuracy, A = 0.9875

iv. % accuracy, a =98.75%

2) Given a 500 V voltmeter with accuracy ±3 full scale Calculate limiting error when the instrument is used to measure a voltage of 350 V?

(ans:15V,4.3%)

3) The expected value of the voltage across a resistor is 50V; however, measurement yields a value of 49V. Calculate

a) The absolute error (ans:1V)

b) The percent of error (ans:2%)

4) The following set of ten measurement was recorded in the laboratory. Calculate the precision of the fourth measurement.

(ans:0.96)

5) Design a volt box that ranges 5V, 10V, 50V and 100V. Each resistor are 40Ω/V. The volt box is used together with a potentiometer with range 2.0V as shown below.

(Ans: R1=80 Ω,VR2=3V, R2=120 Ω, VR3=5V, R3=200 Ω, VR4=1.6k Ω and R4=2k Ω)

6) A two dials potentiometer consists of 20 stages of main dial. Every stage is 20 Ω, with each stage represent 0.2V. A slide wire resistance is 20 Ω with division scale of 200. The working battery is 12 V. Calculate:

a) Working current. (10mA)

b) The measurement range. (4.2V)

c) The adjusted rheostat value. (780 Ω)

7)A potentiometer has a slide wire of 200 cm with overall resistance 100 Ω, and a 3V working battery. The internal resistance is neglected. This instrument is standardized with a reference voltage source of 1.019 V and the sliding contact is set to 101.9cm during the calibration process. Calculate:

a) Working current. (20mA)

b) The measurement range, V(AB). (2V)

c) The adjusted rheostat value. (50 Ω)