A galvanometer may be converted into ammeter or a voltmeter. In which of the following cases the resistance…
A galvanometer may be converted into ammeter or a voltmeter. In which of the following cases the resistance of the device so obtained will be the largest?
Ammeter of range 1 A
Ammeter of range 10 A
Voltmeter of range 1 V .
Voltmeter of range 10 V
Solution
A voltmeter always has high resistance as R is in series.
To increase the range of voltmeter i.e., to increase V , its resistance must increase.
$\therefore \quad$ High range $\Rightarrow$ high resistance.
$\therefore \quad$ Voltmeter of range 10 V has the largest resistance.