Question

When a current of 5 mA is passed through a galvanometer having a coil of resistance 15 `Omega`, it shows full scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range 0-10 V is ____________.

Options

• `2.535 xx 10^3  Omega`

• `4.005 xx 10^3  Omega`

• `1.985 xx 10^3  Omega`

• `2.045 xx 10^3  Omega`

Answer 1

When a current of 5 mA is passed through a galvanometer having a coil of resistance 15 `Omega`, it shows full scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range 0-10 V is `1.985 xx 10^3  Omega`.

Explanation:

`"Given:"  "G" = 15  Omega and "I"_"g" = 5 xx 10^-3 "A"`

Let series resistance be R.

`therefore "V" = "I"_"g" ("R" + "G")`

`therefore 10 = 5 xx 10^-3 ("R" + 15)`

`therefore "R" = 2000 - 15 = 1985`

` = 1.985 xx 10^3  Omega`