The electromagnetic spectrum

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Question 3
Medium

Some therapeutic devices use different ranges of infrared (IR) radiation.

Table 1 shows the frequency ranges for three bands of infrared radiation: IR-A, IR-B, and IR-C.

Table 1

Infrared BandFrequency range (Hz)
IR-C3.0 × 1011 to 1.0 × 1013
IR-B1.0 × 1013 to 2.1 × 1014
IR-A2.1 × 1014 to 4.3 × 1014

Figure 1 shows how these different bands of infrared radiation penetrate human skin layers.

Diagram showing a cross-section of human skin with three layers from top to bottom: Epidermis, Dermis, and Subcutaneous tissue. Three arrows representing IR-C, IR-B, and IR-A enter from the top. The IR-C arrow is very thick and terminates entirely in the Epidermis. The IR-B arrow is medium-width, penetrates the Epidermis, and terminates in the Dermis. The IR-A arrow is thinner, penetrates through both the Epidermis and Dermis, and terminates in the deep Subcutaneous tissue. Arrow width represents the relative amount of radiation.

Describe how the penetration of infrared radiation into skin layers changes with wavelength, using information from Table 1 and Figure 1.

Calculations are not required.

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The electromagnetic spectrum Questions

  1. GCSE
  2. /Physics
  3. /The electromagnetic spectrum