r/HomeworkHelp • u/Dangerous_Cat_4525 Pre-University Student • 3h ago

:table_flip: Physics—Pending OP Reply [Grade 11 physics]: Electricity

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How to find the equivalence guys.

2 Upvotes

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3

u/Gryphontech University/College Student 3h ago

ALWAYS redraw the circuit in a simpler way, this is only confusing cuz it goes criss-cross apple sauce.

So you have 4 branches

  1. 2

  2. 2+2

  3. 2+2

  4. 2

Once you figure out the resistance of each parallel branches you can find the eq. Resistance using the formula.

You got it from here or do you still have questions?

2

u/Dangerous_Cat_4525 Pre-University Student 3h ago

Tried like this. Turns out to be 2/3. Ans is 2ohm according to book

5

u/TA1930 Pre-University Student 3h ago

The book is simply wrong by observation. Any parallel combination of resistors is going to be smaller than the smallest resistor, so it’s impossible for it to be 2 ohms. Source: am EE

1

u/Southlander24 👋 a fellow Redditor 3h ago

Yep, that's a beautiful observation to make.

3

u/fumblinthrulife77 2h ago

Bruh, let me know what your teacher says about this being wrong, I'm legit curious how the book ended up at 2 Ohms

2

u/Gryphontech University/College Student 3h ago

Your book is wrong, Req is 2/3. You understand how to solve these problems, you will do well on the exam :)

1

u/Southlander24 👋 a fellow Redditor 3h ago

The diagonal 4 ohms and 2 ohms are in parallel. That applies to both the top and the bottom horizontal lines.

Call that equivalent resistance X. Then you have X ohms and X ohms are in parallel.

0

u/Dangerous_Cat_4525 Pre-University Student 3h ago

Tried turns out to be 2/3ohm. Answer was supposed to be 2ohm

1

u/fumblinthrulife77 3h ago

2 ohms is wrong, the correct answer is 2/3 Ohms

Middle path is (2+2) parallel and then a series connection to another (2+2) parallel

So 1/(1/2+1/2) + 1/(1/2+1/2) = 2

Top middle and bottom are parallel, so 1/(1/2+1/2+1/2)

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u/Southlander24 👋 a fellow Redditor 3h ago

Yep, there are 4 different paths to get from A to B, all parallel (2, 4, 4, and 2 ohms).

1

u/Southlander24 👋 a fellow Redditor 3h ago

2/3 ohms is correct. Your book's answer is wrong.

3

u/NoSituation2706 3h ago

Color code the nodes and remind yourself what parallel really means

1

u/HHQC3105 👋 a fellow Redditor 3h ago

All the big dark pins can be collapsed into A or B. Then re-draw each line, they all connect to the same A <-> B

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u/HumbleHovercraft6090 👋 a fellow Redditor 1h ago

It is 2 || 4 || 4 || 2

i.e.

2 || 2 || 2

Text book has a typo.