Question

Eels are able to generate current with biological cells called electroplaques. The electroplaques in an Eel are arranged in $100$ rows, each row stretching horizontally along the body of the fish containing $5000$ electroplaques. The arrangement is suggestively shown below.

Each electroplaques has an emf of $0.15\text{V}$ and internal resistance of $0.25\Omega$. The water surrounding the Eel completes a circuit between the head and its tail. If the water surrounding it has a resistance of $500\Omega$, the current an eel can produce in water is about -

• A. $1.5\text{A}$
• B. $3.0\text{A}$
• C. $3.5\text{A}$
• D. $4.0\text{A}$

Answer 1

The correct option is A $1.5\text{A}$


Let the current in each row be $i$.

Hence, current in water is contributed by each row and total current in water becomes $100i$.

Applying Kirchhoff's Voltage Law to row and water,

$5000E-\left(5000r\right)i-500\left(100i\right)=0$

$\Rightarrow i=\frac{5000E}{5000r+50000}=\frac{5000\times 0.15}{5000\times 0.25+50000}$

$\Rightarrow i=0.015\text{A}$

So, current in water is $100i=1.5\text{A}$