An electromagnetic wave propagating in a vacuum can be characterized by its wavelength λ \lambda\,λ and frequency fff. Let λX\lambda_{\text{X}}λX and fXf_{\text{X}}fX represent the wavelength and frequency of an X-ray in a vacuum, and let λIR\lambda_{\text{IR}}λIR and fIRf_{\text{IR}}fIR represent the wavelength and frequency of an infrared wave in a vacuum.
Which of the following relationships is always correct?
λXfX>λIRfIR\lambda_{\text{X}} f_{\text{X}} > \lambda_{\text{IR}} f_{\text{IR}}λXfX>λIRfIR
fXfIR=λXλIR\frac{f_{\text{X}}}{f_{\text{IR}}} = \frac{\lambda_{\text{X}}}{\lambda_{\text{IR}}}fIRfX=λIRλX
fXλIR>fIRλXf_{\text{X}} \lambda_{\text{IR}} > f_{\text{IR}} \lambda_{\text{X}}fXλIR>fIRλX
fXλIR<fIRλXf_{\text{X}} \lambda_{\text{IR}} < f_{\text{IR}} \lambda_{\text{X}}fXλIR<fIRλX
32 exam-style questions on OCR GCSE Physics The electromagnetic spectrum. Each one has a worked solution and a mark scheme showing where the marks go.