National League for Nursing (NLN PAX) Practice Exam

Which type of light can also emit electrons from a photosensitive surface alongside blue light?

1. Infrared light

2. Visible light

3. Ultraviolet light

4. X-ray light

The correct answer is: Ultraviolet light

Ultraviolet light is capable of emitting electrons from a photosensitive surface, a phenomenon known as the photoelectric effect. This occurs because ultraviolet light has a higher energy than visible light and is able to impart enough energy to electrons, allowing them to be ejected from the surface of certain materials. In this context, the ability to emit electrons is not limited to blue light, which is part of the visible spectrum; rather, ultraviolet light is particularly effective due to its higher energy photons. Other types of light, such as infrared light, typically have lower energy and do not possess the requisite energy to release electrons effectively. Visible light also does not consistently have enough energy to cause electron emission across all materials, as it has a range of energies. Similarly, X-ray light, while also high in energy, is a different spectrum entirely and is typically associated with interactions in high-energy physics and healthcare imaging rather than standard photoelectric effects observable in laboratory conditions. Thus, ultraviolet light stands out as the correct answer due to its well-established role in ionizing effects and the photoelectric emission of electrons from photosensitive materials.