Question

A
voltmeter of0to 250v has an error of Full
scale deflection. if the
of voltmeter is 25v
the range
of its reading
voltage
is
(i 22.5 V- 27.50
(1) 27.5V - 29.5V
(iv) 24V - 120v
(v) 25.5v – 26.5v.​

Answer 1

The voltmeter can show an error of +/- 2% of full scale i.e., +/- 6 V (+/- 0.02×300= =+/- 6) whatever may be the measured voltage. So the reading would be 24 V (30–6) to 36 V (30+6).

So it is observed that the error is 6V for 30V of reading i.e., 20%.

Hence it is understood that % of error increases as the measurand (quantity being measured) value becomes lesser than the full scale reading.

So it is always encouraged to use a instrument whose full scale value is nearer the measurand value.

= 24 V-120 V