Electricity, with D as the reference point, find the voltage between each point and C and D. Why is vb negative? Please draw the reference direction and explain the reason, thank you!
(1) when d is the reference point, VA =-30V.
(2) Because point D is the reference point, that is, VD = 0.
The potential at point D is higher than that at point A (current flows from high potential to low potential).
So va = uad =-6 * 5 =-30 (v)