# 2015 Evaluative

Its finally up :)

- Created by: 3sho1416
- Created on: 02-02-15 14:08

First 270 words of the document:

Capacitor discharge

1 Read information given and setup

circuit as shown.

2 Time value (e.g. 10s) and resistor value

given

3 Draw table for figures found from

Voltmeter (three readings for accuracy +

find an average) n> number of capacitors

(when adding more capacitors add in

series), do 5/6 at least

V> Voltage in Voltmeters(/V)

n V 1/V V 2/V V 3 /V V Avg/V lnV0

1 e.g.2.20 2.20 2.19 2.20 0.788

2

3

4 Draw graph in(V/V) (yaxis) against n(xaxis). + Line of best fit. (graph

should look like this:

5 Determine yintercept of graph drawn = mine 0.860 V

6 Gradient of graph (draw triangle within first and last point = dy/dx) do this twice

then find average, my gradient = 0.0789

hn

V = V

0e

7 Where V 0 is the initial p.d. across the arrangement of capacitors and h is a

constant. Use your values of gradient and yintercept to determine a value

for h and to confirm your value V 0.

(Here rearrange above equation to show equation of line drawn by you from

the experiment that you carried out)

Write out in this layout

hn

V = V0e

lnV=lnV 0 hn

lnV= hn+ lnV 0

Gradient =h Xaxis=n lnV0 =yintercept

Hence initial voltage V0= e(value of yintercept)

0.860

Mine V0= e

V0 = 2.36V (it's never higher than e.m.f value of cell)

8 k= gradient , so determine Capacitance

K=t/CR

C= answer in Farads

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