Question

The current sensitivity of a galvanometer increase by 20%. If its resistance also increases by 25%, the voltage sensitivity will ______.

पर्याय

• decrease by 1%

• increased by 5%

• increased by 10%

• decrease by 4%

Answer 1

The current sensitivity of a galvanometer increase by 20%. If its resistance also increases by 25%, the voltage sensitivity will decrease by 4%.

Explanation:

Given, `"I'"_"g" = "I"_"g" + 20/100 "I"_"g"`

`= 120/100 "I"_"g" = 1.2  "I"_"g"`

R' = R + `25/100 "R" = 125/100 "R"`

= 1.25 R

`"V'"_"g"` = ?

`"V'"_"g" = "I'"_"g"/"R'" = (1.2 "I"_"g")/(1.25  "R")`

`= 120/125 "V"_"g" = 25/25 "V"_"g"`

% change = `("V'"_"g" - "V"_"g")/"V"_"g" xx 100`

`= ((24/25 "V"_"g" - "V"_"g"))/"V"_"g" xx 100`

`= ((24 - 25))/25 xx 100`

`= (-1)/25 xx 100`

= 4%