Question

which best explains why one laser beam might appear blue and another laser beam might appear red?
the energy in laser beams is concentrated.
the energy in laser beams is scattered.
each laser beam is made up of all visible wavelengths of light.
each laser beam is made up of one specific wavelength of light.

Explanation:

• Lasers are monochromatic, meaning they consist of a single wavelength of light.
• Different colors (like blue and red) correspond to different wavelengths.
• If a laser beam is red, it has a longer wavelength (\(\lambda_{red}\approx 620 - 750\space nm\)) compared to a blue laser beam (\(\lambda_{blue}\approx 450 - 495\space nm\)).
• Option 1: The concentration of energy in a laser beam does not explain the color difference.
• Option 2: Scattering of energy in a laser beam is not relevant to color variation.
• Option 3: Lasers are not made up of all visible wavelengths (that would be white light, like from a regular light bulb).

Answer:

Each laser beam is made up of one specific wavelength of light.