Physics- P7 Part D 0.0 / 5 ? PhysicsMagnetism and ElectromagnetismGCSEAQA Created by: 13clarkenCreated on: 31-05-18 10:50 38462715 Across 1. Transformers are almost 100% ... (9) 5. ... transformer: Increases the PD. They have more turns on secondary coil than primary coil (4, 2) 6. ... transformer: Decreases the PD. They have more turns on primary coil than secondary coil (4, 4) Down 2. ... change the size of the PD for an alternating current. They have primary and secondary coils of wire, joined with an iron core. The alternating PD is applied across primary coil, iron core magnetises and demagnetises quickly and then to secondary (12) 3. ... are loudspeakers in reverse. Sound waves hit the flexible diaphragm attached to a coil of wire, wrapped around a magnet. This causes a wire to move in magnetic field and generates a current. Movement of coil depends on properties of sound waves (11) 4. ... show how the PD generated changes over time. For AC, the PD is positive and negative. For DC, the PD is positive only. The height of line is the generated PD and increasing frequency, increases the overall PD (13) 7. ... work the same way as generators but have a split ring commutator instead of slip rings and brushes. This swaps connection every half-turn, so there is a DC and not an AC (7) 8. ... rotate a coil in a magnetic field. As coil spins, a current is induced, and changes direction every half turn. Contacts don't swap every half turn as they have slip rings and brushes instead of split ring commutators. They produce alternating PD (10)
Comments
No comments have yet been made