# 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

#### 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

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