Question

Find the equivalent resistance across P and Q​

Answer 1

Given:

• A circuit diagram is given to us .

To Find:

• The equivalent resistance across points P and Q .

Concept Used:

• We will make use if formula to find the equivalent resistance when resistors are connected in parallel and series.

Answer:

Firstly have a look at the formulae ,

For , 3 resistors (say) connected in series,

$\large{\underline{\boxed{\red{\sf{\leadsto R_{net}=R_{1}+R_{2}+R_{3}}}}}}$

$\rule{200}1$

For , 3 resistors (say) connected in parallel,

$\large{\underline{\boxed{\red{\sf{\leadsto \dfrac{1}{R_{net}}=\dfrac{1}{R_{1}}+\dfrac{1}{R_{2}}+\dfrac{1}{R_{3}}}}}}}$

Firstly ,two 10Ω resistors are in series ,So ,

Net resistance = 10Ω + 10Ω = 20Ω.

Now this equivalent resistance is in parallel to 5Ω resistor. So ,

1/Net resistance = 1/5Ω + 1/20Ω = 4+1/20Ω =

5/20Ω = 1/4Ω

Hence net resistance = 4Ω .

Now , this net resistance 4Ω , 2Ω and 3Ω are in series . So ,

Net resistance = 4Ω + 2Ω + 3Ω = 9Ω.

Hence the net resistance across points P and Q is 9Ω.