Quantitative

Question 1

Step 1?

Answer 1

Close switch, record V0 to nearest 0.1/0.01V

1 mark

Open switch + start timer, record V at 20s.

1 mark

Repeat twice then average

1 mark

Question 2

Step 2?

Answer 2

Add a second capacitor in series by twisting cables together.

Close switch, open switch and record V at 20s.

Repeat for up to 6 capacitors

Record data

Question 3

Marks for step 2?

Answer 3

1 - 6 set
1 - headings and units
1 - V to nearest 0.1 or 0.01V
1 - lnV correct
1 - lnV correct dp - (same as voltage or one more)
1 - quality data

Question 4

Table headings?

Answer 4

n - number of capacitors
V1
V2
V3?
Vavg
Ln(V)

Question 5

Step 3?

Answer 5

Plot lnV (y) against n (x) graph
Find gradient (negative)
Find y intercept

Question 6

Marks for step 3?

Answer 6

1 - correct labels, scales and points
1 - plotted points take up more than half piece of paper
1 - correct plots
1 - best fit line
1 - gradient correct
1 - read off lnV at n=0

Question 7

Step 4?

Answer 7

Find k (POSITIVE gradient value)
Find V0 = e^yintercept
Find C using k=t/(CR) - units are CV^-1 ? C is capacitance

2 marks

Put C,k to 2/3 sig.figs. (1mark)
Justify no of sig figs used (1mark)

Question 8

Describe set up?

Answer 8

Power pack, then voltmeter, resistor and capacitor (positive to positive with power pack) in parallel, then switch just before negative terminal.

1 mark