Resistance is measured by the voltmeter ammeter method. The voltmeter reading is 50 V on 100 Volts scale and ammeter reading is 50 mA on 100 mA scale.
Resistance is measured by the voltmeter ammeter method. The voltmeter reading is 50 V on 100 Volts scale and ammeter reading is 50 mA on 100 mA scale. If both the meter are guaranteed for accuracy within 2% of full scale, the limit within which resistance is measured will be
Right Answer is:
80Ω
SOLUTION
Given Reading on voltmeter and ammeter is
V = 50 V
I = 50 mA
Resistance R = V/I = 50/50 × 10−3 = 1KΩ
Limiting error in voltmeter at full scale is
δE = ± 2% of 100
δE = ±2V
Thus when the reading is 50 V, the error will still be 2 V. Hence the % limiting error
= (2/50)x100 = 4%
Limiting error in ammeter at full scale is
δE = ± 2% of 100
δE = ±2mvA
Thus when the reading is 50mA, the error will still be 2mA. Hence the % limiting error
= (2/50) × 100 = 4%
Total Limiting Error = 4% + 4% = 8%
Limiting Error value of resistance
8% of 1000 = 8 × 1000⁄100 = 80Ω