A 5 ohm resistor is connected in series combination with a parallel combination of n resistors of 6 ohm . the equivalent resistance is 7 ohm. find value of n
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4 resistances can be formed by series and parallel combination of all 3 resistances.
Consider 3 resistances each of value R.
1. When all three are connnected in a seriescombination the equivalent resistance is 3R.
2. When any two of them are connected inparallel and one in series with them the equivalent resistance will be
(R×R/(R+R))+R=R/2+R=3/2R
3. When any two of them are connected inseries and one is connected in parallel then the effective resistance will be
(2R×R/(2R+R))=2/3R
4. When all three resistances are connected inparallel then the effective resistance will be
From point no.2 we can take the resistance of two resistances in parallel which is R/2
Hence the equivalent of three parallel will be R/2×R/(R/2+R)=R/3
Two more resistances can be obtained by putting any two in series(2R) and any two in parallel(R/2).
Consider 3 resistances each of value R.
1. When all three are connnected in a seriescombination the equivalent resistance is 3R.
2. When any two of them are connected inparallel and one in series with them the equivalent resistance will be
(R×R/(R+R))+R=R/2+R=3/2R
3. When any two of them are connected inseries and one is connected in parallel then the effective resistance will be
(2R×R/(2R+R))=2/3R
4. When all three resistances are connected inparallel then the effective resistance will be
From point no.2 we can take the resistance of two resistances in parallel which is R/2
Hence the equivalent of three parallel will be R/2×R/(R/2+R)=R/3
Two more resistances can be obtained by putting any two in series(2R) and any two in parallel(R/2).
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