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HELP PLEASE Physics Capacitance

Just a quick question 5b I don't understand:
http://pmt.physicsandmathstutor.com/download/Physics/A-level/Topic-Qs/OCR-A/6-Particles-and-Medical-Physics/6.1-Capacitors/Set-M/Capacitors%201%20QP.pdf

It says to find the volt across the 150 microfarad capacitor; so I did 150/600 * 6V to get 1.5V however, the markscheme says its wrong and it should be 4.5V??? Can someone please explain - many thanks :smile:

MS: http://pmt.physicsandmathstutor.com/download/Physics/A-level/Topic-Qs/OCR-A/6-Particles-and-Medical-Physics/6.1-Capacitors/Set-M/Capacitors%201%20MS.pdf
Well as the MS says charge is constant is a series circuit (because current is constant) so if C=Q/V then capacitance is inversely proportional to voltage so lower capacitance=higher share of voltage
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MrToodles4
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Original post by Somebody1234
Well as the MS says charge is constant is a series circuit (because current is constant) so if C=Q/V then capacitance is inversely proportional to voltage so lower capacitance=higher share of voltage


Many thanks for the reply - so is this ALWAYS the case in a series circuit with a capacitor???
Original post by MrToodles4
Many thanks for the reply - so is this ALWAYS the case in a series circuit with a capacitor???


I suppose so, tbh idk what exam board u do but ive never seen an edexcel question with 2 capacitors in series
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MrToodles4
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Original post by Somebody1234
I suppose so, tbh idk what exam board u do but ive never seen an edexcel question with 2 capacitors in series


So what calculation would you use for this then? Cause mine gives the answers in the wrong way around. Its OCR A.
Original post by MrToodles4
So what calculation would you use for this then? Cause mine gives the answers in the wrong way around. Its OCR A.


Its all about ratios u cant really think of it as a single calculation thatll get u to the answer
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MrToodles4
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Original post by Somebody1234
Its all about ratios u cant really think of it as a single calculation thatll get u to the answer


Alright so basically I just need to remember to swap them, so that 1.5V i worked out would be for the high capacitance capacitor
Original post by MrToodles4
Alright so basically I just need to remember to swap them, so hat 1.5V i worked out would be for the high capacitance capacitor


Ok well if uve got 2 capacitors in series u can literally do V=EMF*(Total capacitance - capacitance)/Total capacitance but that equation stops working if u have more than 2, but as u said up there that way of thinking works fine

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