Question

The velocity of light in vacuum can be changed by changing (A) frequency (B) wavelength (C) amplitude (D) none of these

Short answer

In a vacuum, the speed of light (c) is a constant value, approximately 3.00 x 10^8 m/s, and is represented as the product of frequency (f) and wavelength (λ) through the equation: c = f * λ. Changes in frequency or wavelength result in corresponding changes in the other variable to maintain the constant speed. Amplitude represents intensity and does not affect the velocity of light in a vacuum. Hence, the correct answer is (D) none of these.

Step-by-step solution

Review the properties of light waves

Light is an electromagnetic wave, and its speed in a vacuum is a constant value denoted by "c." The speed of light in a vacuum is about 299,792,458 meters per second (approximately 3.00 x 10^8 m/s). Electromagnetic waves have several properties, such as frequency, wavelength, and amplitude.

Define frequency, wavelength, and amplitude

Frequency is the number of wave cycles per second, measured in Hertz (Hz). Wavelength is the distance between two consecutive points in a wave, such as two adjacent crests or troughs, and it is typically measured in meters (m). Amplitude is the maximum displacement of a point in the wave from its mean position, and it represents the intensity of the wave.

Understand the relation between frequency, wavelength, and speed of light

In a vacuum, the speed of light (c) can be represented as the product of frequency (f) and wavelength (λ), as described by the equation: c = f * λ As the speed of light is a constant value in a vacuum, if we change either the frequency or the wavelength of light, the other variable will also change accordingly to maintain the constant speed.

Examine the effect of amplitude on the speed of light

The amplitude of an electromagnetic wave represents its intensity or energy level, not its speed. Changes in amplitude do not affect the velocity of light in a vacuum.

Choose the correct answer

Based on the analysis of the properties of light and the relationship between frequency, wavelength, and speed, it is clear that neither frequency, wavelength, nor amplitude can alter the speed of light in a vacuum. Thus, the correct answer is: (D) none of these

Key concepts

Properties of Light Waves

Light, as an electromagnetic wave, possesses key properties that include frequency, wavelength, and amplitude. These properties are integral to understanding how light behaves.
- **Frequency:** This refers to how many cycles of the wave occur per second, measured in Hertz (Hz). - **Wavelength:** The distance between successive crests or troughs of a wave, usually measured in meters (m). - **Amplitude:** This indicates the maximum displacement of the wave from its rest position, which correlates directly to the intensity of the light.
The interplay of these properties defines the characteristics and behavior of light in various mediums. It's crucial to note that while light's speed can alter in different mediums like water or glass, in a vacuum, it always remains constant at approximately 299,792,458 meters per second.

Frequency and Wavelength Relation

The frequency and wavelength of light are closely tied together through the equation \(c = f \cdot \lambda\), where \(c\) is the speed of light, \(f\) is the frequency, and \(\lambda\) represents the wavelength.
This relationship implies a delicate balance: if one property changes, the other will adjust to maintain the constant speed of light in a vacuum. For instance: - **High Frequency:** Results in a shorter wavelength. - **Low Frequency:** Corresponds to a longer wavelength.
Understanding this relationship helps explain various phenomena, such as why ultraviolet light (high frequency) carries more energy and is potentially more harmful than infrared light (low frequency). Despite changes in frequency or wavelength, the speed of light remains constant. This constancy is a fundamental aspect of how electromagnetic waves behave in a vacuum.

Amplitude and Light Intensity

Amplitude measures the peak value or strength of the light wave's oscillation, and it is directly linked to the intensity of light.
Light intensity, or brightness, is determined by how much energy is carried by the wave in a certain direction per unit area, often measured as power per unit area (like watts per square meter).
- **Higher Amplitude:** Means higher light intensity or brightness. - **Lower Amplitude:** Corresponds to dimmer light.
It's essential to recognize that amplitude does not affect the speed of light in a vacuum. Changes in amplitude impact only the energy carried by the wave, not its velocity. This distinction is important for differentiating how light behaves when interacting with materials and when it's traveling through a vacuum.