The visible portion of the electromagnetic spectrum is __________.
light
Understanding the Visible Electromagnetic Spectrum
The electromagnetic spectrum is the range of all types of electromagnetic radiation. Radiation is energy that travels and spreads out as it goes – visible light is just one type of electromagnetic radiation. Other types include radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays, and gamma rays.
These different types of radiation are distinguished by their wavelengths and frequencies. The entire spectrum spans a vast range, but only a small portion of it is detectable by the human eye. This specific portion is what we call the visible spectrum, or simply visible light.
Identifying the Visible Portion
The question asks to identify the visible portion of the electromagnetic spectrum. Let's look at the options provided:
- Infrared: This is part of the electromagnetic spectrum, located just below the visible light in terms of energy and frequency (longer wavelength). It is not visible to the human eye, although we can feel it as heat.
- Radiowave: These are the longest wavelengths in the electromagnetic spectrum and have the lowest frequencies and energy. They are used for communication but are not visible.
- Microwave: These waves are shorter than radio waves but longer than infrared waves. They are used in ovens and communication but are not visible.
- Light: This term commonly refers to visible light, the portion of the electromagnetic spectrum that our eyes can perceive. This visible light spectrum ranges from red (longest wavelength, lowest frequency) to violet (shortest wavelength, highest frequency).
Based on the definition and properties of the electromagnetic spectrum, the visible portion is indeed light.
| Type of Radiation | Wavelength Range (approx.) | Frequency Range (approx.) | Visible to Humans? |
|---|---|---|---|
| Radio waves | > 1 mm | < 300 GHz | No |
| Microwaves | 1 mm - 1 meter | 300 MHz - 300 GHz | No |
| Infrared | 700 nm - 1 mm | 300 GHz - 430 THz | No |
| Visible light | 400 nm - 700 nm | 430 THz - 750 THz | Yes |
| Ultraviolet | 10 nm - 400 nm | 750 THz - 30 PHz | No |
| X-rays | 0.01 nm - 10 nm | 30 PHz - 30 EHz | No |
| Gamma rays | < 0.01 nm | > 30 EHz | No |
The visible light spectrum is a continuous range of colours: red, orange, yellow, green, blue, indigo, and violet (often remembered by the acronym ROYGBIV). The wavelengths for these colors span roughly from 400 nanometers (violet) to 700 nanometers (red).
Conclusion on Visible Spectrum
The question asks for the visible portion of the electromagnetic spectrum. Out of the given options, only 'light' (referring to visible light) fits this description. Infrared, radiowave, and microwave are all parts of the electromagnetic spectrum but are invisible to the human eye.
Revision Table: Key Concepts
| Concept | Description |
|---|---|
| Electromagnetic Spectrum | The range of all types of EM radiation. |
| Visible Spectrum | The part of the EM spectrum visible to human eyes. |
| Visible Light | Another term for the visible spectrum. |
| Wavelength | Distance between successive crests of a wave (\(\lambda\)). |
| Frequency | Number of waves passing a point per unit time (\(f\)). |
| Speed of Light | Constant speed of all EM waves in a vacuum (\(c \approx 3 \times 10^8\) m/s). Relation: \(c = \lambda f\). |
Additional Information: Properties of Electromagnetic Waves
Electromagnetic waves are transverse waves that consist of oscillating electric and magnetic fields. They do not require a medium to travel and can propagate through the vacuum of space. All electromagnetic waves travel at the same speed in a vacuum, which is the speed of light, denoted by \(c\). The energy of an electromagnetic wave is directly proportional to its frequency. This means that higher frequency waves (like gamma rays and X-rays) carry more energy than lower frequency waves (like radio waves and microwaves).
The different parts of the electromagnetic spectrum have various applications:
- Radio waves: Broadcasting, communication (radio, TV, mobile phones).
- Microwaves: Cooking, satellite communication, radar.
- Infrared: Heat sensing, thermal imaging, remote controls.
- Visible light: Vision, photography, illumination, fiber optics.
- Ultraviolet: Sterilization, medical therapy, causing sunburn.
- X-rays: Medical imaging, security scanning.
- Gamma rays: Medical treatment (radiotherapy), sterilization.
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Which of the following is correct?
I. Sound is a mechanical wave
II. Sound wave does not need any medium to propagate
At a particular temperature, sound propagates in ______ at the fastest speed .
The atmospheric green house effect is produced mainly by the absorption and re-emission of:
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a. Television waves
b. Ultraviolet rays
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When light passes from one medium into another medium, then the physical property which does not change is
