Question 21N.2.HL.TZ0.3

«electric field at P from one charge is $\frac{kQ}{r^2}=$» $\frac{8.99\times {10}^9\times 44\times {10}^{-6}}{0.{48}^2}$

OR

$1.7168\times {10}^6$ «NC⁻¹» ✓

« net field is » $2\times 1.7168\times {10}^6\times \cos 30°=2.97\times {10}^6$ «NC⁻¹» ✓

directed vertically up «on plane of the page» ✓

Allow an arrow pointing up on the diagram.

force «on q» is proportional to the displacement ✓

and opposite to the displacement / directed towards equilibrium ✓

$«a=\frac{F}{m}=»{\omega }^{2}x=\frac{115x}{0.25}$ ✓

$T=«\frac{2\mathrm{\pi }}{\omega }=» 0.29 «\text{s}»$ ✓

Award [2] marks for a bald correct answer.

Allow ECF for MP2.

decreasing from 12 ✓

correct shape as shown ✓

Do not penalize if the graph does not touch the t axis.

$\frac{1}{2}=e^{-\frac{5.0}{20\times {10}^6 C}}$ ✓

$C=3.6\times {10}^{-7}$ «F» ✓

Award [2] for a bald correct answer.