| Date | November 2017 | Marks available | 1 | Reference code | 17N.3.SL.TZ0.2 |
| Level | Standard level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | State | Question number | 2 | Adapted from | N/A |
Question
An electrical circuit is used during an experiment to measure the current I in a variable resistor of resistance R. The emf of the cell is e and the cell has an internal resistance r.
A graph shows the variation of 1I with R.
Show that the gradient of the graph is equal to 1e.
[2]
a.
State the value of the intercept on the R axis.
[1]
b.
Markscheme
«ε = IR + Ir»
1I=Rε+rε
identifies equation with y = mx + c
«hence m = 1ε»
No mark for stating data booklet equation
Do not accept working where r is ignored or ε = IR is used
OWTTE
a.
«–» r
Allow answer in words
b.
Examiners report
[N/A]
a.
[N/A]
b.
