An engineer uses an ultrasound transducer to perform non-destructive testing on a thick glass-fibre reinforced polymer (GFRP) wind turbine blade.
In a healthy, defect-free section of the blade, the transducer transmits an ultrasound pulse at time t=0t = 0t=0 and subsequently detects a single clear, high-amplitude reflected pulse RB R_B\,RB from the rear boundary of the polymer section.
In a section containing a localized internal delamination (a narrow air gap between composite layers), the transducer detects a very low-amplitude reflected pulse RD R_D\,RD at an earlier time, followed by a pulse of reduced amplitude from the rear boundary.
Suggest one physical reason why the amplitude of the pulse reflected from the delamination defect (RDR_DRD) is significantly smaller than the amplitude of the pulse reflected from the rear boundary of the healthy section (RBR_BRB).
35 exam-style questions on Edexcel GCSE Physics 4.3 Sound, ultrasound and infrasound (physics only). Each one has a worked solution and a mark scheme showing where the marks go.