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"Two automobile batteries are connected in parallel to power a wheelchair. If each of the batteries has an emf = 12.0 V and internal resistance r = .020 ohms, and the wheelchair motor has a resistance R = 1.00 Ohms, find the current provided to the motor. What would be the current delivered to the motor if the batteries were connected in series? What are the relative advantages of series and parallel connections?"

Work thus far:

I used 3 equations to solve for the current across the wheelchair.

I(1) + I(2) = I(3) (Current In = Current Out)

-I(1)r(1) + emf - I(3)R = 0 (Circuit loop 1)

-I(2)r(2) + emf - I(3)R = 0 (Circuit loop 2)

Solving for I(3) after 4-5 lines:

I(3) = (2*emf*r) / (2r-2Rr)

I(3) = -12.1 Amps.

I wasnt really expecting a negative answer. I have the current over R from negative to positive, thus I'm not totally sure why its negative.

I havnt done series yet because I wanted to confirm the work I did for // first.

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# Homework Help: Parallel Batteries.

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