# What is the Potential Difference Between c and d in This Circuit?

• gracy
In summary: When you simplify component networks you lose analytical access to nodes that get absorbed into the replacement components. Sometimes you just have to leave some components unsimplified to retain access to nodes you need.
Similarly here
##V_i##=##I####R_i##=##V_{in}####\frac{R_i}{R_1+R_2+...+R_n}##

Read #40. I have added to the "Relevant equations". When you take these into account you can solve this problem in 10 seconds... unless you prefer to be a pedantic student, but I see no virtue in taking days you could use for other study or something else over a 10 s problem.

gracy said:
Should not it be ##V_i##=Q/##C_i##=##V_{in}####\frac{1/C_i}{1/C_1+1/C_2+...+1/C_n}##
Yes, thank you . I corrected it. You see how easy it is to make mistakes!
Yes i denotes any random element.
You can also notice that in case all n components of the chain are equivalent, the voltage across one of them is Vin/N . That was epenguin suggested you in #40.

gracy
gracy said:
in the picture why ##V_{Rn}## =##I####R_n## and ##V_{Cn}##=##\frac{Q}{C_n}## is not shown
Good catch! That's down to me getting sloppy with the cut & paste to duplicate the expressions, forgetting to "touch up" those entries.

I've updated the picture.

gracy

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