Question

How will the reading of ammeter change if the key $k$ is closed?

• A. Increases
• B. Decreases
• C. Remains same
• D. Information is insufficient

Answer 1

The correct option is A Increases

Here, the reading of ammeter shows current passing through the source.

Case 1: When the key is open,


$R_{eq}=3R/2$

So, $i_1=\frac{V}{3R/2}=\frac{2V}{3R}$

Case 2: When the key is closed.


$R_{eq}=\frac{2R}{3}+\frac{2R}{3}=\frac{4R}{3}$

$\Rightarrow i_2=\frac{V}{4R/3}=\frac{3V}{4R}$

Since, $i_2>i_1$

So, the reading of Ammeter increases.

Hence, option $\left(a\right)$ is the correct answer.