Question

An ammeter of resistance 20Q gives full-scale deflection when 1 mA current flows through it. What is the maximum current that can be measured by connecting 4 resistors each of 16Q in parallel with the ammeter?

विकल्प

• 6 mA

• 4 mA

• 8 mA

• 2 mA

Answer 1

6 mA

Explanation:

Given, G = 20Q and 1_g = 1mA = 1 x 10^-3 A

The equivalent resistance of 4 resistors of 16 Q each, connected in parallel is
`"R"_"eq"="R"/"n"=16/4=4 Omega`

The circuit diagram of an ammeter is

So, the maximum current that can be measured,

`"l"=("l"_"g""G"+"l"_"g""R"_"eq")/"R"_"eq"=("l"_"g"("G"+"R"_"eq"))/"R"_"eq"`

`=(1xx10^3(20+4))/4`

= 6 x 10^-3 A or 6 mA