A student designs the coil for an electric motor.
Each side of the coil that is in the magnetic field has 40 turns of wire. The length of one turn of wire in the magnetic field is 3.0 cm.
The magnetic flux density is 0.35 T0.35\ \text{T}0.35 T. The current in the coil is 0.80 A. The sides of the coil are at right angles to the magnetic field.
Calculate the force on one turn of wire on one side of the coil.
Use the equation
F=B×I×lF = B \times I \times lF=B×I×l
Give your answer in standard form.
Calculate the total force on one side of the coil.
Explain why increasing the number of turns on the coil makes the motor turn faster.
The student uses thinner wire so that more turns fit on the coil. The potential difference across the coil is unchanged.
Explain why the force on each turn of wire may decrease.
86 exam-style questions on Edexcel GCSE Physics 12.3 The motor effect, covering 12.3.1 The motor effect, 12.3.2 Fleming's left-hand rule, 12.3.3 Force on a conductor, and 12.3.4 Electric motors. Each one has a worked solution and a mark scheme showing where the marks go.