| Date | November 2016 | Marks available | 3 | Reference code | 16N.2.SL.TZ0.7 |
| Level | Standard level | Paper | Paper 2 | Time zone | Time zone 0 |
| Command term | Estimate and State | Question number | 7 | Adapted from | N/A |
Question
The graph shows how current I varies with potential difference V for a resistor R and a non-ohmic component T.
(i) State how the resistance of T varies with the current going through T.
(ii) Deduce, without a numerical calculation, whether R or T has the greater resistance at I=0.40 A.
Components R and T are placed in a circuit. Both meters are ideal.
Slider Z of the potentiometer is moved from Y to X.
(i) State what happens to the magnitude of the current in the ammeter.
(ii) Estimate, with an explanation, the voltmeter reading when the ammeter reads 0.20 A.
Markscheme
i
RT decreases with increasing I
OR
RT and I are negatively correlated
Must see reference to direction of change of current in first alternative.
Do not allow “inverse proportionality”.
May be worth noting any marks on graph relating to 7bii
ii
at 0.4 A: VR > VT or VR= 5.6 V and VT = 5.3 V
Award [0] for a bald correct answer without deduction or with incorrect reasoning.
Ignore any references to graph gradients.
so RR >RT because V = IR / V∝ R «and I same for both»
Both elements must be present for MP2 to be awarded.
i
decreases
OR
becomes zero at X
ii
realization that V is the same for R and T
OR
identifies that currents are 0.14 A and 0.06 A
Award [0] if pds 2.8 V and 3.7 V or 1.4 V and 2.6V are used in any way. Otherwise award [1 max] for a bald correct answer. Explanation expected.
2 V = 2 V OR 2.0 V
