27. Find the effective resistance (in Ω) between A and B
a. 5
C. 15
b. 10
d. 20
Answers
Ans:
Answer is A.
The circuit can be reduced, step by step, to a single equivalent resistance. The 5 ohm and the 5 ohm that are connected to terminal A are in series, and so they can be replaced by an equivalent resistor Rs1 of 10 ohms, using the equation Rs=5+5=10 ohms.
This resistance Rs1 of 10 ohms is now connected parallely to another 10 ohms resistance. This connection can be reduced to a single equivalent resistance Rp. They are connected in series and the equivalent resistance Rp is given as below.
Rp
1
=
10
1
+
10
1
=5 ohms.
Now the resistances Rp and 5 ohms are connected in series and the equivalent resistance Rs2 is given as Rs2=5+5=10 ohms.
The resistances Rs1 and the remaining 10 ohm resistance are connected parallely and hence, the total resistance in the circuit is given as follows.
R
1
=
10
1
+
Rs2
1
=
10
1
+
10
1
=5 ohms
Hence, the resistance across the terminals A and B is 5 ohms.