Electric fish generate current with biological cells called electro-plaques, which are physiological emf devices. The electro-plaques in the South American eel are arranged in \(140\) rows, each row stretching horizontally along the body and each containing \(5000\) electro-plaques. Each electro-plaque has an emf of \(0.15{\rm{ }}V\) and internal resistance of \(0.25{\rm{ }}\Omega \). If the water surrounding the fish has resistance of \(800{\rm{ }}\Omega \), how much current can the eel produce in water from near its head to near its tail?

Electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or a vacuum. The electric charge flow rate through a surface or into a control container is measured as a net rate.

• Number of rows:\({n_r} = 140\)
• Number of electro-plaques:\(n = 5000\)
• Emf of each electro-plaque:\({E_c} = 0.15{\rm{ }}V\)
• Internal resistance of each electro-plaque:\({R_c} = 0.25{\rm{ }}\Omega \)
• Resistance of water: \({R_w} = 800{\rm{ }}\Omega \)

If electro-plaques are arranged in rows, it means that they are connected in serial series. This means that we can calculate their max voltage as:

\(\begin{aligned}{}E &= {E_c}n\\E & = 0.15 \times 5000\\E & = 750\;V\end{aligned}\)

and their resistance per row

\(\begin{aligned}{}{R_\tau } & = {R_c}n\\{R_\tau } & = 0.25 \times 5000\\{R_\tau } & = 1250{\rm{ }}\Omega \end{aligned}\)

We can calculate how much current can pass through each row:

\(\begin{aligned}{}{R_t} & = {R_r} + {R_w}\\{R_t} & = 1250 + 800\\{R_t} & = 2050{\rm{ }}\Omega \end{aligned}\)

\(\begin{aligned}{}{I_t} & = \frac{E}{{{R_t}}}\\{I_t} & = \frac{{750}}{{2050}}\\{I_t} & = 0.366\;A\end{aligned}\)

All combined we get:

\(\begin{aligned}{}I & = {I_t}{n_r}\\I & = 0.366 \times 140\\I & = 51.2\;A\end{aligned}\)

Therefore, the current value is \(I = 51.2\;A\).