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

The ink glows under ultraviolet (UV) radiation because UV light transfers energy to the ink, causing it to absorb the UV light energy. This absorbed energy is then re-emitted at a lower frequency as visible light, which we perceive as fluorescence.

To find the wavelength ( ( \lambda ) ) of the electromagnetic wave, we can use the formula:

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

where:

( v = 3 \times 10^8 \text{ m/s} )

( f = 7 \times 10^7 \text{ Hz} ) Substituting the values:

$\lambda = \frac{3 \times 10^8}{7 \times 10^7}$

Evaluating this gives:

$\lambda = 4.29 \text{ m}$

Thus, the wavelength is approximately 0.043 m.

Excessive exposure to different regions of the electromagnetic spectrum can lead to various health issues:

1. Ultraviolet (UV) Radiation: Prolonged exposure can cause skin burns, accelerated skin aging, and increase the risk of skin cancers such as melanoma.

2. X-rays and Gamma Rays: These ionizing radiations can damage cellular DNA, leading to mutations and an increased risk of cancers. They can also cause tissue damage at high exposures.

3. Radiofrequency Radiation (RF): While generally considered low risk, excessive RF exposure from devices like cell phones has been debated regarding potential links to brain tumors and other health concerns over prolonged use.

4. Microwave Radiation: High levels of microwave exposure can cause heating of body tissues, potentially leading to burns or other thermal injuries.

5. Electromagnetic Fields (EMF): Long-term exposure to certain frequencies of EMF might disrupt cellular function, though research is still ongoing to fully understand these effects.

In summary, while some electromagnetic radiations are harmful only in excessive amounts, protection measures should be observed to minimize risks.