Edexcel A-Level Physics Assessed Mathematical Skills

Which of the following derived units can be expressed in SI base units as $\mathrm{kg} \mathrm{m}^{2} \mathrm{~s}^{-3}$ ?

A student investigated the behaviour of a thermistor using the circuit shown in the diagram.

She heated the thermistor to 100 °C and measured the potential difference V across it. She decreased the temperature θ and recorded further measurements of V and θ until the temperature reached 10 °C.

A student used a laser and screen to determine the diameter of a hair. The apparatus was arranged as shown.

The student repeated the procedure using three different lasers. Each laser produced a different wavelength of light.

The student calculated the diameter d of the hair using each laser. He recorded the values as shown.

Determine the mean value of d.

Mean value of d=

A student investigated the photoelectric effect using the apparatus shown.

He used a source of white light and colour filters to shine different wavelengths $\lambda$ 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 $V_{\mathrm{s}}$ when the current in the photocell was zero.
He calculated the maximum kinetic energy $E_{\text {max }}$ of the photoelectrons for each wavelength of light.

The table shows the student's data.

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

Percentage difference =