From Ek=hf−W, the gradient of Ek versus f is h.
Using the first and third points:
h≈(9.0−7.0)×10141.23−0.40=4.15×10−15eV s.
Using Ek=h(f−f0) with the first point,
f0=7.0×1014−4.15×10−150.40=6.04×1014Hz.
Then
W=hf0=(4.15×10−15)(6.04×1014)=2.51eV.
Rounding to the precision of the data gives about 2.50eV.
Recognises gradient as Planck constant.
[1 mark]
Calculates gradient.
[1 mark]
Uses intercept relationship.
[1 mark]
Calculates threshold frequency.
[1 mark]
Calculates work function.
[1 mark]
Uses data with appropriate precision.
[1 mark]
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.