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

The ink is fluorescent because it absorbs energy from the ultraviolet (UV) radiation and re-emits it as visible light. Under normal light, the ink does not emit visible light, making it appear invisible.

The relationship between wavelength ($\lambda$), frequency ($f$), and speed of light ($v$) is given by:

$\lambda = \frac{v}{f}$

Substituting the values:

$\lambda = \frac{3 \times 10^8 \text{ m/s}}{7 \times 10^7 \text{ Hz}}$

Calculating the wavelength:

$\lambda = 4.2857 \text{ m}$

Rounded to two decimal places, the wavelength is approximately $0.04$ m.

Excessive exposure to electromagnetic radiation can lead to various health issues, including:

UV Radiation

Ultraviolet radiation can cause skin damage, including sunburn and increased risk of skin cancer due to DNA damage in skin cells.

X-rays and Gamma Rays

Ionizing radiation such as X-rays and gamma rays can damage cellular DNA, potentially leading to cancer and other tissue damage.

Radiofrequency Radiation

Prolonged exposure to radiofrequency radiation, such as from mobile phones, is under investigation for potential links to tumors, although evidence remains inconclusive.

Microwaves

Excessive exposure to microwave radiation can cause heating of body tissues, leading to burns or other injuries.

Overall, the impact of radiation on the human body depends on factors such as the type of radiation, duration of exposure, and the individual's health.