Electric fish generate current with biological cells called electroplaques, which are physiological emf devices. The electroplaques in the South American eel are arranged in 140 rows, each row stretching horizontally along the body and each containing 5000 electroplaques. Each electroplaque has an emf of 0.15 V and an internal resistance of 0.25 Ω. If the water surrounding the fish has a resistance of 800Ω. How much current can the eel produce in water from near its head to near its tail?

current in water = 0.924 A

Explanation:

Let the current in each row be i.

Thus, current in water is contributed by each row and total current in water becomes 140i.

We are given;

emf of each electroplaque = 0.15 V

Number of electroplaques = 5000

internal resistance = 0.25 Ω

resistance = 800Ω

Applying Kirchoff's Voltage Law to row and water, we have;

5000E - (5000r) i - 800 (140i) = 0

Rearranging;

5000E = (5000r) i + 800 (140i)

Plugging in the relevant values;

5000 x 0.15 = i ((5000 x 0.25) + 112,000)

750 = 113,250i

i = 750/113,250

i = 0.0066 A

Recall earlier, the current in water is 140i.

Thus, current in water = 140 x 0.0066

= 0.924