Understanding the Wavelength of Violet Light

Light is a form of electromagnetic radiation that travels in waves. The wavelength of light is the distance between successive crests or troughs of the wave. Different colours of visible light correspond to different wavelengths.

The visible light spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. It consists of a range of colours, commonly remembered by the acronym ROYGBIV: Red, Orange, Yellow, Green, Blue, Indigo, and Violet.

Each of these colours occupies a specific range of wavelengths within the visible spectrum. Red light has the longest wavelength, while violet light has the shortest wavelength.

Let's look at the approximate wavelength ranges for the colours in the visible spectrum:

The question asks for the approximate wavelength of violet colour light. Based on the typical ranges, violet light is found at the shorter wavelength end of the visible spectrum, approximately between 380 nm and 420 nm.

Now let's examine the given options:

1. 10 - 11 pm: Picometers (pm) are much smaller units than nanometers (nm). $1\text{ nm} = 1000\text{ pm}$. So, 10 - 11 pm is $0.010 - 0.011$ nm, which is far too short for visible light. This range is characteristic of X-rays or gamma rays.
2. 1 - 10 mm: Millimeters (mm) are much larger units than nanometers. $1\text{ mm} = 1,000,000\text{ nm}$. So, 1 - 10 mm is $1,000,000 - 10,000,000$ nm, which is far too long for visible light. This range is characteristic of microwaves or radio waves.
3. 455 - 390 nm: This range, although listed from a slightly longer to a shorter wavelength, spans from 390 nm to 455 nm. This range falls within and slightly extends the typical range for violet and indigo light (380-450 nm), placing it squarely in the region of violet colour light.
4. 230 - 310 pm: As discussed, picometers are very small. 230 - 310 pm is $0.230 - 0.310$ nm, also too short for visible light, characteristic of X-rays.

Comparing the options to the known wavelength range for violet light, the range 455 - 390 nm (or 390 - 455 nm) is the only one that falls within or very close to the expected wavelengths for violet light.

Revision Table: Key Light Wavelengths

Additional Information on Electromagnetic Spectrum and Wavelengths

Visible light is just a small part of the vast electromagnetic spectrum. The electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

• Radio waves have wavelengths that can be kilometers long.
• Gamma rays have wavelengths shorter than a picometer.

Units commonly used for wavelength measurement depend on the region of the spectrum:

• Radio waves: meters (m), kilometers (km)
• Microwaves: centimeters (cm), millimeters (mm)
• Infrared, Visible, Ultraviolet: nanometers (nm)
• X-rays, Gamma rays: picometers (pm)

Understanding these units and the typical wavelengths associated with different types of electromagnetic radiation is crucial in physics.

• $1 \text{ meter (m)} = 10^9 \text{ nanometers (nm)}$
• $1 \text{ nanometer (nm)} = 10^{-9} \text{ meters (m)}$
• $1 \text{ picometer (pm)} = 10^{-12} \text{ meters (m)}$
• $1 \text{ millimeter (mm)} = 10^{-3} \text{ meters (m)}$

The visible light spectrum generally ranges from about 380 nm (violet) to about 750 nm (red).