The fact that I 2 and I 3 are both negative indicates that the wrong directions

Question

The fact that I2 and I3 are both negative indicates that the wrong directions were chosen for these currents. Nonetheless, the magnitudes are correct. Choosing the right directions of the currents at the outset is unimportant because the equations are linear, and wrong choices result only in a minus sign in the answer.

QUESTION Is it possible for the current through a battery to be directed from the positive terminal toward the negative terminal? (Select all that apply.)

Yes. It happens inside a rechargeable flashlight battery or a car battery during recharge.Yes. It can happen when the voltage applied to a battery is greater than its emf.No. The charge carriers inside a battery is never reversible.

PRACTICE IT

EXERCISE HINTS:  GETTING STARTED  |  I'M STUCK!

Find the three currents in figure b, where R = 1.6 . (Note that the direction of one current may have been chosen wrongly!)

Explanation / Answer

Question :

During charging of a battery the current flows into the battery

Yes. It happens inside a rechargeable flashlight battery or a car battery during recharge.

and also during chrarging V = e+(i*r)

Yes. It can happen when the voltage applied to a battery is greater than its emf.

PRACTICE IT

Apply KVL to the top loop

-e+(6*I1)-10-(4*I2) = 0

6I1 - 4I2 = 25 ..............(1)

Apply KVL to the bottom loop

10-(6I1)-(2*I3) = 0

6*I1 + 2*I3 = 10..........(2)

at junction c

I1+I2 -I3 = 0 .........(3)

Solving (1),(2) and (3) we get

I1 = 2.04 A

I2= -3.18 A

and I3 = -1.13 A

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