SI units and prefixesAQA A-Level Physics: Mind map

Exam questions on SI units and prefixes

1. A technician is checking the units on a data sheet for a mechanics practical involving force, pressure, energy and power.
   Pressure is force per unit area. Show that the pascal can be written in SI base units as kg m⁻¹ s⁻².2 marks
2. A student is converting between units of energy used in two contexts: a household electricity meter, which records energy in kilowatt-hours, and a particle physics data table, which gives energies in electronvolts. Use e = 1.60×10⁻¹⁹ C.
   A kettle of power 2.2 kW is switched on for 4.5 minutes. Calculate the energy transferred, in kW h.2 marks
3. A green laser pointer emits light of wavelength 532 nm with a power of 5.0 mW. Each photon from the laser has an energy of 2.33 eV. Use e = 1.60×10⁻¹⁹ C.
   Write the wavelength in metres and the power in watts, both in standard form, and calculate the energy emitted by the laser in 60 s.3 marks