The electromagnetic spectrum is continuous - Edexcel - GCSE Physics - Question 5 - 2013 - Paper 1

The ink glows under ultraviolet radiation because it fluoresces. Ultraviolet (UV) radiation transfers energy to the ink, exciting its electrons. When these electrons return to their ground state, they emit energy in the form of visible light, causing the ink to glow.

Using the formula for wavelength, ext{wavelength} ( ext{λ}) = rac{v}{f} we substitute the known values: ext{λ} = rac{3 imes 10^8 ext{ m/s}}{7 imes 10^7 ext{ Hz}} This calculation gives us: $ext{λ} = 4.29 imes 10^{-1} ext{ m} = 0.043 ext{ m}$

Excessive exposure to electromagnetic radiation can have several harmful effects on the human body, including:

1. Ultraviolet Radiation: Overexposure can cause skin damage, such as sunburn and an increased risk of skin cancer, as it damages the DNA in skin cells.

2. X-rays: High doses can lead to cellular damage and an increased risk of cancer due to ionization of atoms in the body.

3. Microwave Radiation: Prolonged exposure can cause tissue heating, potentially leading to burns and affecting internal organs.

4. Radiofrequency Radiation: This can also affect cellular function and increase the risk of tumors, particularly with excess mobile phone usage.

5. Electromagnetic Fields (EMF): Long-term exposure might contribute to various health issues, including headaches and fatigue, although research is still ongoing.

Each type of radiation interacts with biological tissues in different ways, and understanding these effects is crucial for public health.