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Edexcel IGCSE Physics 2.6 Ac and Dc Questions

Use current direction and oscilloscope traces to identify a.c. and d.c., then explain how diodes and LEDs respond when current alternates.

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

Edexcel IGCSE Physics 2.6 Ac and Dc Questions 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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