HELP PLEASE Physics Capacitance Watch

MrToodles4
Badges: 10
Rep:
?
#1
Report Thread starter 1 year ago
#1
Just a quick question 5b I don't understand:
http://pmt.physicsandmathstutor.com/...s%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

MS: http://pmt.physicsandmathstutor.com/...s%201%20MS.pdf
0
reply
Somebody1234
Badges: 8
Rep:
?
#2
Report 1 year ago
#2
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
Posted on the TSR App. Download from Apple or Google Play
0
reply
MrToodles4
Badges: 10
Rep:
?
#3
Report Thread starter 1 year ago
#3
(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???
0
reply
Somebody1234
Badges: 8
Rep:
?
#4
Report 1 year ago
#4
(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
Posted on the TSR App. Download from Apple or Google Play
0
reply
MrToodles4
Badges: 10
Rep:
?
#5
Report Thread starter 1 year ago
#5
(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.
0
reply
Somebody1234
Badges: 8
Rep:
?
#6
Report 1 year ago
#6
(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
Posted on the TSR App. Download from Apple or Google Play
0
reply
MrToodles4
Badges: 10
Rep:
?
#7
Report Thread starter 1 year ago
#7
(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
0
reply
Somebody1234
Badges: 8
Rep:
?
#8
Report 1 year ago
#8
(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
Posted on the TSR App. Download from Apple or Google Play
1
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • Solent University
    Postgraduate and Professional Open Evenings Postgraduate
    Mon, 25 Mar '19
  • Cardiff University
    Undergraduate Open Day Undergraduate
    Wed, 27 Mar '19
  • University of Portsmouth
    Postgraduate and Part-Time Open Evenings Postgraduate
    Wed, 27 Mar '19

Where do you need more help?

Which Uni should I go to? (141)
18.24%
How successful will I become if I take my planned subjects? (78)
10.09%
How happy will I be if I take this career? (132)
17.08%
How do I achieve my dream Uni placement? (110)
14.23%
What should I study to achieve my dream career? (76)
9.83%
How can I be the best version of myself? (236)
30.53%

Watched Threads

View All
Latest
My Feed