Question

Label each of the following statements as true or false. For those that are false, correct the statement. (a) Visible light is a form of electromagnetic radiation. (b) Ultraviolet light has longer wavelengths than visible light. (c) X-rays travel faster than microwaves. (d) Electromagnetic radiation and sound waves travel at the same speed.

Short answer

(a) TRUE - Visible light is a form of electromagnetic radiation. (b) FALSE - Ultraviolet light has shorter wavelengths than visible light. (c) FALSE - X-rays and microwaves travel at the same speed. (d) FALSE - Electromagnetic radiation and sound waves travel at different speeds.

Step-by-step solution

Statement (a) - Visible light as electromagnetic radiation

Visible light is indeed a form of electromagnetic radiation. Electromagnetic radiation encompasses a range of wavelengths and frequencies that includes visible light, with each color corresponding to a specific range of wavelengths. This statement is TRUE.

Statement (b) - Ultraviolet light's wavelengths compared to visible light

Ultraviolet light is also a form of electromagnetic radiation. When comparing it to visible light, ultraviolet light has SHORTER wavelengths, not longer. Therefore, this statement is FALSE. The correct statement should be: "Ultraviolet light has shorter wavelengths than visible light."

Statement (c) - X-rays vs. microwaves speed

Both X-rays and microwaves are forms of electromagnetic radiation. All forms of electromagnetic radiation travel at the same speed in a vacuum, which is the speed of light (approximately \(3.0 \times 10^8\) meters per second). Therefore, this statement is FALSE. The correct statement should be: "X-rays and microwaves travel at the same speed."

Statement (d) - Electromagnetic radiation and sound waves speed

Electromagnetic radiation and sound waves are two different types of waves. Electromagnetic radiation consists of oscillating electric and magnetic fields, and it travels at the speed of light. Sound waves, on the other hand, are vibrations that travel through a medium, such as air or water, at a speed that depends on the properties of the medium. In air, sound travels at approximately \(343\) meters per second, which is much slower than the speed of light. Therefore, this statement is FALSE. The correct statement should be: "Electromagnetic radiation and sound waves travel at different speeds."

Key concepts

Visible Light

Visible light is a fascinating component of the electromagnetic spectrum. It represents the portion of electromagnetic radiation that is detectable by the human eye. Electromagnetic radiation spans a wide range of wavelengths and frequencies, but only a small part is visible to us. This range is typically from about 380 nanometers (nm) at the violet end to about 750 nm at the red end.

• Each color of visible light corresponds to a particular wavelength range. For example, violet light has shorter wavelengths, whereas red light has longer wavelengths within the visible spectrum.
• The visible spectrum is often remembered by the acronym "ROYGBIV," which stands for Red, Orange, Yellow, Green, Blue, Indigo, and Violet.

Understanding visible light is crucial not just for scientific purposes but for practical applications like designing lighting systems and studying optical phenomena. The colors we perceive from objects are a direct result of the wavelengths of light they reflect or emit.

Ultraviolet Light

Ultraviolet (UV) light occupies the region of the electromagnetic spectrum beyond the violet end of visible light. This means it has shorter wavelengths than visible light, typically ranging from 10 nm to 400 nm. Despite being invisible to the human eye, UV light plays an essential role in various natural and artificial processes.

Ultraviolet light can be further categorized into three main types based on wavelength:

• UVA (long-wave, 320-400 nm) - This type of UV light accounts for approximately 95% of the UV radiation reaching the Earth's surface. It can penetrate the skin more deeply and contribute to skin aging and wrinkling.
• UVB (medium-wave, 290-320 nm) - Mostly absorbed by the ozone layer, UVB is crucial for vitamin D production in humans but also causes sunburn and contributes to skin cancer risk.
• UVC (short-wave, 100-280 nm) - The ozone layer absorbs most UVC, so it typically doesn't reach the ground. It is effective in killing bacteria and viruses and is used in sterilization processes.

Despite its potential dangers, ultraviolet light is vital for life and has beneficial applications in various fields, including medicine and environmental science.

Speed of Light

The speed of light is a fundamental constant in physics that represents the maximum speed at which most energy, information, or matter can travel. In a vacuum, light travels at approximately \[3.0 \times 10^8\] meters per second. This unparalleled speed is why light can circle the Earth more than seven times in just one second!

Light's speed, however, can change when it passes through different materials, such as air, water, or glass, which we call a medium. The slowing of light in these materials happens because of interactions with the matter it encounters. This effect causes phenomena like refraction, which is the bending of light rays as they pass through substances of different densities.

• Changes in speed are responsible for everyday effects like how a straw looks bent when placed in water.
• The speed of light influences many scientific theories, including Einstein's theory of relativity, which postulates that nothing can travel faster than light in a vacuum.

Understanding the speed of light not only helps in grasping more complex physics concepts but also is fundamental in technologies like GPS, where precise time measurement based on light speed ensures accurate positioning. It's an essential part of how we interact with and understand the universe.