A certain meter has a sensitivity of 50000 Ω/V. The electric current required to defect the meter movement to full scale will be
Current = Voltage ⁄ Resistance = 1 ⁄ 50,000 = 20 μA.
The percentage limiting error, in case of an instrument reading of 8.3 V with a 0 to 150 V voltmeter having a guaranteed accuracy of 1% full scale reading is
Max error = 1% of 150 V = 1.5 V percentage limiting error = ( 1.5 ⁄ 8.3 ) × 100 = 18.10%.
An electrically deflected CRT has a final value anode voltage of 2000 V and parallel deflecting plates 1.5 cm long and 5 mm apart. If the screen is 50 cm from the centre of deflecting plate. Find the deflection sensitivity of the tube?
S = ( l × ld) / (2d × Ea) = ( 0.5 × 1.5 × 10 - 2) ⁄ (2 × 5 × 10-3 × 2000 ) = 0.375 mm ⁄ V.
Errors due to human mistakes are
Gross errors occur because of mistakes in observed readings or using instruments and in recording and calculating measured results.
Sensitivity factor of a strain gauge is normally of the order of
1.5-2.0 is the sensitivity factor of strain gauge. The strain gauge is one of the most widely used strain measurement sensors. It is a resistive elastic unit whose change in resistance is a function of applied strain. We know dR / R = Sε where R is the resistance, ε is the strain, and S is the strain sensitivity factor of the gauge material.
The sensitivity of a voltmeter using 0 to 5 mA meter movement is-
Sensitivity = I ⁄ IB = 1 ⁄ 5 mA = 200 Ω / Volt
A compensated wattmeter has its reading corrected for error due to the
A compensated wattmeter has its reading corrected for error due to power consumed in potential coil.