Calculate the current I3 in the following circuit:

Question

BlackTom AI · Accepted Answer

Apply Kirchhoff’s Current Law (KCL): the algebraic sum of currents at a node is zero, so the sum of currents entering the node equals the sum leaving it.

Identify currents and directions from the diagram:
- I1 = 7 A enters the node from the left (into the node).
- I4 = 3 A enters the node from below (upward into the node).
- I2 = 2 A leaves the node upward (away from the node).
- I3 is the unknown leaving the node to the right (arrow shown to the right).

Write KCL as "entering = leaving":
I1 + I4 = I2 + I3

Substitute the known values:
7 A + 3 A = 2 A + I3

Combine left-hand terms:
10 A = 2 A + I3

Solve for I3:
I3 = 10 A − 2 A
I3 = 8 A

Intermediate arithmetic steps shown: 7 + 3 = 10, then 10 − 2 = 8.

Why this is correct: KCL enforces charge conservation at the node; the two incoming currents (7 A and 3 A) supply 10 A total, and 2 A leaves upward, so the remaining 8 A must leave to the right as I3. The positive sign indicates the assumed direction (to the right) matches the actual current direction in the diagram.

Why the other choices are incorrect:
- 2 A would ignore one or more incoming currents (e.g., 7 − 3 = 4 or other incorrect combinations).
- −8 A would have the correct magnitude but the wrong sign, implying the current actually flows left instead of the shown right.
- −2 A is both wrong magnitude and sign.

Therefore I3 = 8 A, which matches the provided correct answer (c. 8A).

Calculate the current I3 in the following circuit:单项选择题

类似问题

Kirchhoff’s Current Law is based on the fact that

At the node picture below, i1 = 5 A, i2 = -1 A and i3 = 3 A. Find ix in Amps.

Three ammeters are located near junction P in a direct current circuit as shown in the diagram below. If ammeter Al reads 3 amperes and ammeter A2 reads 4 amperes, then what does ammeter A3 read?

Question 30 Choose a, b, c or d as the best answer. The author’s main argument is that the 100:80:100 model __________.

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单