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Edexcel A-Level Physics Pulse-Echo Techniques

Practise Edexcel A-Level Physics pulse-echo techniques through ultrasound timing, two-way distances, resolution and boundary reflections.

Syllabus
Pearson Edexcel International Advanced Subsidiary/Advanced Level
Course
Physics XPH11/YPH11
Level
AS

Exam points

  • use echo time with a two-way path to calculate speed, depth or distance to a boundary
  • explain high-frequency ultrasound by linking shorter wavelength to improved resolution
  • identify cracks or air gaps by comparing returned pulse times with expected echo times

2.3.56 - Pulse-echo techniques question 1

[Maximum number: 7]

Rolled steel joists (RSJs) are used in the construction of buildings, as shown.

Figure for Question 2.3.56 - Pulse-echo techniques question 1 — Edexcel A-Level Physics AS

The strength of an RSJ is greatly reduced if there are air gaps within the steel. Ultrasound is used to detect any air gaps in the RSJ.

Pulses of ultrasound are sent by a transducer into an RSJ as shown. Any returning ultrasound is detected by the transducer.

Figure for Question 2.3.56 - Pulse-echo techniques question 1 — Edexcel A-Level Physics AS

Question (a)

(a)

Explain how this arrangement can be used to show whether the RSJ contains an air gap.

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Question (b)

(b)

Ultrasound is a sound wave with a frequency greater than 20 kHz. The frequency of ultrasound used by the transducer in this method is 5 MHz.

Explain why a much higher frequency than 20 kHz is needed in this method.

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