EduNinja

Edexcel A-Level Physics A2 Ratios, Fractions and Percentages

Edexcel A-Level Physics A2 Ratios, Fractions and Percentages
Pearson Edexcel International Advanced Subsidiary/Advanced Level in Physics, Issue 3, July 2021Physics XPH11/YPH11

Review ratios, fractions and percentages in Edexcel A-Level Physics through coefficient ranges, percentage difference and accepted-value comparisons.

How this is tested

  • use ratios or squared quantities such as e² to compare a result with a material range
  • calculate percentage difference using the accepted value as the denominator before judging agreement

Question 4(a)(iv)

[Maximum number: 2]

A student investigated the photoelectric effect using the apparatus shown.

Figure for Question 4(a)(iv) — Edexcel A-Level Physics A2

He used a source of white light and colour filters to shine different wavelengths λ\lambda of light onto the photocell.

Photoelectrons were emitted with a range of kinetic energies, creating a small current in the photocell.

Using the potentiometer, the student varied the potential difference across the photocell. As the potential difference across the photocell increased, the current in the photocell decreased.

He measured the potential difference VsV_{\mathrm{s}} when the current in the photocell was zero.
He calculated the maximum kinetic energy Emax E_{\text {max }} of the photoelectrons for each wavelength of light.

The table shows the student's data.

Table for Question 4(a)(iv) — Edexcel A-Level Physics A2

Calculate the percentage difference between h and the accepted value for the Planck constant.

Percentage difference =