Simple equivalent resistance question

[shivam01anand]

Homework Statement

how many minimum no of resistances of eash 2Ω resistance can be connected to have an effective resistance of 1.5Ω

Homework Equations

The Attempt at a Solution

I tried to put 2 in parallel,series and different combinations.


After 5-10 mins of relentless trying i could not figure the answer[ I know it now ans=4 ( 3 in series with one in parallel)


My point being how to really get hold of this "type" of problem very quickly(objective type q).

and if its not too much could you point out some more similar questions to this on the internet for a grasp on this "Type" of question?

Thanks

 

[tiny-tim]

hi shivam01anand!

My point being how to really get hold of this "type" of problem very quickly(objective type q).

you're looking for a factor of 3/4

you only get fractions from parallel, so start with 2 parallel to 1 (doesn't work), then 3 parallel to 1 (does work, in this case), then 4 parallel to 1, then 3 parallel to 2, and so on …

in fact, why not write out a table of all combinations now, up to say 7, to give you practice and to see how it works? ​