03 Jul, 2021 10:25 PM

In the following figure, what is the value of the potential at points a and b? (Figure 1) Will give best answer?

my answer was 15,2 orignially but it said to check my signs and I don't know how to determine the signs Please I'll give best answer

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03 Jul, 2021 10:26 PM

I have commented link on both your messages

03 Jul, 2021 10:26 PM

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03 Jul, 2021 10:26 PM

drawing requires a sign in.

update: Assuming you want voltage with respect to ground.

point a is +5V

Current in loop is CW and is equal to (15–5)v / (4+1)Ω = 10/5 = 2 amps

voltage drop across 1Ω resistor is E = IR = 2 volts

so Vb = –2v

edit: to elaborate a bit on that last number:

start at ground and go CW around the loop. Voltage at point a is –2 volts

next point is –2+15 = +13.

next point is –2+12–8 = +5v

next point is back to ground, 0v.