| Date | May 2018 | Marks available | 3 | Reference code | 18M.2.SL.TZ1.4 |
| Level | Standard level | Paper | Paper 2 | Time zone | Time zone 1 |
| Command term | Calculate | Question number | 4 | Adapted from | N/A |
Question
An ohmic conductor is connected to an ideal ammeter and to a power supply of output voltage V.
The following data are available for the conductor:
density of free electrons = 8.5 × 1022 cm−3
resistivity ρ = 1.7 × 10−8 Ωm
dimensions w × h × l = 0.020 cm × 0.020 cm × 10 cm.
The ammeter reading is 2.0 A.
Calculate the resistance of the conductor.
Calculate the drift speed v of the electrons in the conductor in cm s–1. State your answer to an appropriate number of significant figures.
Markscheme
1.7 × 10–8 × \(\frac{{0.10}}{{{{(0.02 \times {{10}^{ - 2}})}^2}}}\)
0.043 «Ω»
[2 marks]
v «= \(\frac{I}{{neA}}\)» = \(\frac{2}{{8.5 \times {{10}^{22}} \times 1.60 \times {{10}^{ - 19}} \times {{0.02}^2}}}\)
0.368 «cms–1»
0.37 «cms–1»
Award [2 max] if answer is not expressed to 2 sf.
[3 marks]
