Question

Eels are able to generate current with biological cells called electro-plaques. The electro-plaques and an eel are arranged in $100$ rows, each row stretching horizontally along the body of the fish containing $5000$ electro-plaques. The arrangement is suggestively shown below. Each electro-plaque 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. $15\text{A}$
• D. $30\text{A}$

Answer 1

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

It is an example of mixed arrangement.
Total potential =$0.15\times 5000=750V$.
Resistance per row=$0.25\times 5000=1250\Omega$
There are $100$ rows, so
Total resistance = $\frac{1250}{100}=12.5\Omega$
It is connected with external resistance of $500\Omega$, so
Total resistance = $500+12.5=512.5\Omega$
Current =$\frac{750}{512.5}=1.5\text{A}$