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This question is about infra red (IR) and ultra violet (UV) radiation - OCR Gateway - GCSE Physics - Question 23 - 2021 - Paper 1
Question 23
This question is about infra red (IR) and ultra violet (UV) radiation. (a) It took humans a long time to discover IR and UV radiation. Suggest two reasons why. 1.... show full transcript
Worked Solution & Example Answer:This question is about infra red (IR) and ultra violet (UV) radiation - OCR Gateway - GCSE Physics - Question 23 - 2021 - Paper 1
Step 1
Suggest two reasons why it took humans a long time to discover IR and UV radiation.
Answer
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Technological limitations: Early scientific instruments were not sensitive enough to detect infrared and ultraviolet radiation.
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Lack of understanding of electromagnetic spectrum: Scientists did not have the theoretical framework required to identify and study these forms of radiation.
Step 2
Calculate the frequency of the UV radiation.
Answer
To find the frequency, we can use the formula:
Rearranging this gives:
ext{frequency} = rac{ ext{wave speed}}{ ext{wavelength}}Substituting the given values:
- Wave speed = m/s
- Wavelength = μm = m
Now, we can calculate:
ext{frequency} = rac{3.0 imes 10^8 ext{ m/s}}{0.18 imes 10^{-6} ext{ m}} \ ext{frequency} = 1.67 imes 10^{15} ext{ Hz} \Rounding this to 2 significant figures gives: