Find the effective resistance of the following

Answers
Answer:
1. 60 ohm
2. 0.53 ohm
3. 5.2 ohm
Answer
1. 60ohm
2. 1.75ohm
3. 9ohm
Explanation:
1. The resistance R1 , R2 and R3 are in series combination.
therefore effective resistance ,R = R1+R2+R3
= 10+ 20+30
=60 ohm
2. R1= 5ohm
R2= 3 ohm
R1 and R2 are in parallel combination
therefore effective resistance =
1/R = 1/R1 +1/R2
1/R = 1/5 + 1/3
R = 15/8
R = 1.75 ohm
3. R1=R2=10 ohm
R3= 5 ohm
R4= 3ohm
R5= 2 ohm
Now R1 and R2 are in series combination
therefore net resistance, R' = 10+10
=20ohm
Now this R' is in parallel combination with R3
therefore net resistance , 1/R'' = 1/R' + 1/R3
1/R'' = 1/20 + 1/5
R"= 20/5 = 4ohm
Now R",R4,R5 are in series combination
therefore effective resistance of circuit,
R= R"+R4+R5
= 4+3+2= 9 ohm