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. All forms of electromagnetic radiation, including X rays and microwaves, travel at the speed of light in a vacuum (\(3 \times 10^8 m/s\)). (d) False. Electromagnetic radiation travels at the speed of light, which is approximately \(3 \times 10^8 m/s\) in a vacuum. Sound waves travel much slower, typically at a speed of \(343 m/s\) in the air at room temperature.

Step-by-step solution

(a) Analyzing the statement about visible light

Visible light is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. We need to verify if the statement is true or false.

(a) Answer

The statement is true. Visible light is indeed a form of electromagnetic radiation.

(b) Analyzing the statement about ultraviolet light

Ultraviolet (UV) light is the portion of the electromagnetic spectrum just beyond the visible light range, with wavelengths shorter than visible light. The statement claims that UV light has longer wavelengths than visible light. Let's check if the statement is true or false.

(b) Answer

The statement is false. Ultraviolet light has shorter wavelengths than visible light.

(c) Analyzing the statement about \(X\) rays and microwaves

X rays and microwaves are both forms of electromagnetic radiation. X rays have shorter wavelengths and higher frequencies than microwaves. The statement claims that X rays travel faster than microwaves. We need to verify if this statement is true or false.

(c) Answer

The statement is false. All forms of electromagnetic radiation, including X rays and microwaves, travel at the speed of light in a vacuum (\(3 \times 10^8 m/s\)).

(d) Analyzing the statement about electromagnetic radiation and sound waves

Electromagnetic radiation (EM) and sound waves are two different types of waves. EM waves are transverse waves and can propagate without a medium, while sound waves are longitudinal waves and need a medium to travel. The statement claims that both of these waves travel at the same speed. We need to verify if the statement is true or false.

(d) Answer

The statement is false. Electromagnetic radiation travels at the speed of light, which is approximately \(3 \times 10^8 m/s\) in a vacuum. Sound waves travel much slower, typically at a speed of \(343 m/s\) in the air at room temperature.

Key concepts

Visible Light

Visible light is a fascinating part of the electromagnetic spectrum. It is the range that our eyes can detect, allowing us to see the world in vibrant colors. This portion of electromagnetic radiation ranges from approximately 380 to 750 nanometers in wavelength. Within this range, each color has its own wavelength; for instance, violet has shorter wavelengths, while red has longer ones.
Electromagnetic radiation includes a wide array of waves such as radio waves, infrared, and X-rays. However, only visible light can be seen without the aid of instruments. This is why it is essential in everyday life, enabling not just sight but also influencing art, design, and various technologies.

Ultraviolet Light

Ultraviolet (UV) light comprises a portion of the electromagnetic spectrum that lies just beyond the visible light range. With shorter wavelengths than visible light, UV light spans from about 10 to 400 nanometers. This places it between visible light and X-rays in terms of energy and wavelength.
UV light is known for its effect on the skin, producing tans and potentially causing sunburns. It is also crucial in sterilization processes due to its ability to kill bacteria and viruses. Moreover, some animals, such as insects, can see UV light, aiding in navigation and food sources. Remember, UV light has more energy than visible light, which is why it can cause chemical changes such as those resulting in sunburn.

X Rays

X rays are part of the electromagnetic spectrum, sharing space with visible light and ultraviolet light yet operating at much shorter wavelengths, spanning from 0.01 to 10 nanometers. Due to their high energy, X rays are capable of penetrating various materials, making them valuable in medical imaging and diagnostics.
These rays are vital tools in detecting fractures, diagnosing illnesses, and conducting security scans. Despite their utility, it's crucial to limit exposure as X rays can cause harm with excessive contact. Unlike visible light, X rays are invisible to the naked eye, yet their high energy allows them to reveal what lies beneath the skin or inside objects.

Sound Waves

Sound waves differ markedly from electromagnetic waves like visible light and X rays. They are mechanical waves that require a medium, such as air, water, or solids, to travel through. This reliance on a medium means sound waves cannot propagate in the vacuum of space, unlike electromagnetic radiation.
The speed of sound is influenced by the medium it travels through. In air at room temperature, sound moves at approximately 343 meters per second, much slower compared to the speed of electromagnetic waves, which travel at the speed of light. Sound waves are longitudinal, meaning that the particle displacement occurs parallel to the direction of wave propagation, unlike electromagnetic waves which are transverse.