Question

Eels are able to generate current with biological cells called electro-plaques. The electro-plaques in 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-palque has an emf of $0.15V$ 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. $1.5A$
• B. $3.0A$
• C. $15A$
• D. $30A$

Answer 1

The correct option is A $1.5A$

n = number of rows

Net EMF =

Net EMF in each row $=(5000\times 0.15)V$

Net resistance in each row $=(5000\times 0.25)\Omega$

Net EMF across $\Omega =\left(\frac{\frac{100\times 5000\times 0.15}{5000\times 0.25}}{\frac{100}{5000\times 0.25}}\right)V$

net EMF $=\frac{\frac{n\epsilon }{r}}{\frac{n}{r}}=750V$

Net resistance $=\frac{5000\times 0.25}{1004\times 100}=\frac{R}{n}=12.\Omega$

Now the circuit becomes as shown in the above figure

current $=\frac{V}{R_{eq}}=\frac{7500}{512.5}=\frac{7500A}{5125}=1.46A\sim 1.5A$