circuit

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[匿名]

2013-03-25 11:25 pm

Find the currents I1, I2, I3 through the respective resistors R1, R2, R3 in the circuit below. Indicate the direction of each current using arrow (eg, up , down, left, or right)

|-----------R1=6 ohms-----------E2 =20V--------------|
|................................|...................................|
|................................|...................................|
|................................|...................................|
E1= 30.0V.................R2= 3 ohms...............R3 = 2 ohms
|................................|...................................|
|................................|...................................|
|................................|...................................|
|__________________|___E3=10.0V_________.|

更新1:

唔好意思.需唔需要用I3

回答 (2)

用戶10012

2013-03-26 12:18 am

✔ 最佳答案

Let current through R1 is I1 from left to right.
Let current through R2 is I2 downwards.
So current through R3 = I1 - I2 downwards.
For E1, assume up side is +ve. For E2 and E3, assume left side is +ve.
For the loop on the left,
30 = 6I1 + 3I2.............(1)
For the loop on the right,
3I2 + 10 = 20 + 2(I1 - I2)
3I2 - 2I1 + 2I2 = 10
- 2I1 + 5I2 = 10 ............(2)
(1) + 3 x (2)
18I2 = 60
I2 = 10/3 A
From (1)
30 = 6I1 + 10
I1 = 10/3
I1 - I2 = 0
Current through R1 = current through R2 = 10/3 A both in the assumed direction. Current through R3 = 0.

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[匿名]

2013-03-26 1:52 pm

唔好意思.需唔需要用I3

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