# Homework Help: Equivalent capacitance:pentagon shape

1. Nov 30, 2015

### gracy

1. The problem statement, all variables and given/known data
Five capacitors ,each of capacitance value C are connected as shown in the figure.The ratio of capacitance between P and R,and the capacitance between P and Q is

2. Relevant equations
For Equivalent Capacitance in series

$\frac{1}{C}$=$\frac{1}{C_1}$+$\frac{1}{C_2}$

3. The attempt at a solution
But I don't know from which direction should I consider capacitors whether clockwise or anticloclwise?Because I will encounter different number of capacitors in each of these direction.

2. Nov 30, 2015

### ehild

Does it matter? is $\frac{1}{C_1}+\frac{1}{C_2}$ not the same as $\frac{1}{C_2}+\frac{1}{C_1}$?What capacitors are connected in series and in parallel with respect to the terminals P and R, and in case when the terminals are P and Q?
Determine the equivalent capacitance between P and R. Then determine the equivalent capacitance between P and Q. What are they?

3. Nov 30, 2015

### azizlwl

It seems to me that you are very interested in capacitors and resistors. I recommend that you buy multitester with capacitance measuring capability. Get few resistors and capacitors of different values and make a circuit of any configuration you like.

4. Nov 30, 2015

### gracy

I will try to solve this with the help of answers I have received in my previous thread.

Now the two capacitors are in parallel
equivalent capacitance between P and R=C/2+C/3
=$\frac{5C}{6}$

Now the two capacitors are in parallel
equivalent capacitance between P and Q is =C+C/4
=$\frac{5C}{4}$
The ratio between the two are
$\frac{5C}{6}$÷$\frac{5C}{4}$

=$\frac{2}{3}$

Am I right?

5. Nov 30, 2015

### Dick

Looks good to me.

6. Nov 30, 2015

### ehild

Splendid!
You did it right, the answers you got in one thread can be applied in an other thread. Do not forget them!

7. Nov 30, 2015

### gracy

Thank you so much for this .

8. Nov 30, 2015

### SammyS

Staff Emeritus
Why did you not do this in OP ?

Then, if you were not sure about which order to use, you could have tried any order you were not sure about and compared answers.

That's generally how we know whether or not such things are important.