A linear motor is being tested. A straight section of its conductor passes through a uniform magnetic field at right angles to the field. A force sensor supports the conductor, which remains stationary during the test. When current flows, the magnetic force acts upwards and the force sensor reading decreases.
The test results are shown in the table.
| Measurement | Value |
|---|---|
| Force sensor reading with no current | 0.286 N |
| Force sensor reading with a current of 3.0 A | 0.250 N |
| Position where the conductor enters the field | 4.0 cm |
| Position where the conductor leaves the field | 10.0 cm |
Calculate the magnetic flux density.
Use F=BIlF=BIlF=BIl.
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.