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Edexcel IGCSE Physics 2.6 AC & DC

Practise distinguishing a.c. and d.c. using circuit components, oscilloscope traces, LEDs, diodes and battery-charging contexts.

Syllabus
First assessment 2019
Course
Physics 4PH1

Exam points

  • describe a.c. as changing direction and d.c. as current in one direction only
  • use an oscilloscope trace crossing positive and negative values as evidence for a.c
  • explain why an LED or diode conducts for only part of an a.c. cycle

2.6 AC and DC question 1

[Maximum number: 3]

Magnetic Resonance Imaging (MRI) machines can take scans of the inside of a patient.

Question (a)

(a)

During the scan, music can be played through a loudspeaker to the patient.

The oscilloscope trace in the diagram represents a sound played to the patient.

Figure for Question (a) — Edexcel IGCSE Physics
[ 3 ]

Question (i)

(i)

The current in the loudspeaker is alternating current (a.c.).

Give the evidence from the oscilloscope trace to support this statement.

[ 2 ]

Question (ii)

(ii)

Draw the circuit symbol for an a.c. power supply.

[ 1 ]
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