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Be sure to show all calculations clearly and state your final answers in complete sentences. Radio Station. What is the wavelength of a radio photon from an AM radio station that broadcasts at 1120 kilohertz? What is its energy?

Short Answer

Expert verified
The wavelength is approximately 267.857 meters, and the energy of the photon is approximately \(7.42512 \times 10^{-28}\) joules.

Step by step solution

01

Concept of Wavelength and Frequency

Wavelength and frequency are inversely related through the speed of light formula: \( c = \lambda \cdot f \), where \( c \) is the speed of light (approximately \(3 \times 10^8\) meters per second), \( \lambda \) is the wavelength in meters, and \( f \) is the frequency in hertz. Our task is to find the wavelength \( \lambda \).
02

Convert Frequency

Convert the given frequency from kilohertz to hertz. Since 1 kilohertz (kHz) is equal to 1000 hertz (Hz), the frequency at 1120 kHz is \( 1120 \times 10^3 \) Hz.
03

Calculate Wavelength

Using the formula \( \lambda = \frac{c}{f} \), where \( c = 3 \times 10^8 \text{ m/s} \) and \( f = 1120 \times 10^3 \text{ Hz} \), plug in the values to find the wavelength:\[\lambda = \frac{3 \times 10^8}{1120 \times 10^3} = \frac{3 \times 10^8}{1.12 \times 10^6} \approx 267.857 \text{ meters.}\]
04

Concept of Photon's Energy

The energy of a photon is calculated using the formula \( E = h \cdot f \), where \( h \) is Planck's constant \( (6.626 \times 10^{-34} \text{ J} \cdot \text{s}) \) and \( f \) is the frequency in hertz. Our task now is to find the energy \( E \).
05

Calculate Energy

Using the formula \( E = h \cdot f \), and substituting \( h = 6.626 \times 10^{-34} \text{ J} \cdot \text{s} \) and \( f = 1120 \times 10^3 \text{ Hz} \), calculate the energy:\[E = 6.626 \times 10^{-34} \times 1120 \times 10^3 = 7.42512 \times 10^{-28} \text{ joules.}\]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Wavelength and Frequency
Understanding the relationship between wavelength and frequency is fundamental in radio wave calculations. These two are inversely connected via the speed of light formula. When you know the frequency of a radio wave, you can find its wavelength, and vice versa.

Frequency (\( f \) ), measured in hertz (Hz), indicates how many wave cycles pass a point in one second. Wavelength (\( \lambda \) ), measured in meters, is the distance between consecutive crests of a wave.

When a radio station broadcasts at 1120 kilohertz, it is the frequency of the wave. We convert kilohertz to hertz by multiplying by 1000, resulting in 1120,000 Hz. By understanding this relationship, we can move on to using the speed of light to find the wavelength.
Speed of Light Formula
The speed of light formula is crucial when examining how light waves, including radio waves, travel through space. The formula is expressed as \( c = \lambda \cdot f \) , where \( c \) represents the speed of light, approximately \( 3 \times 10^8 \text{ m/s} \), \( \lambda \) is the wavelength in meters, and \( f \) is the frequency in hertz.

This formula demonstrates that as frequency increases, wavelength decreases, maintaining a constant speed for all electromagnetic waves.

To find the wavelength of the radio wave from our example, we rearrange the formula to \( \lambda \) = \( \frac{c}{f} \). Plugging in the values \( c = 3 \times 10^8 \text{ m/s} \) and \( f = 1120 \times 10^3 \text{ Hz} \), we calculate \( \lambda \approx 267.857 \text{ meters} \). This tells us how long each wave is from crest to crest.
Planck's Constant
Planck's constant is a key factor in quantum mechanics and in calculating the energy of photons. It is a fundamental physical constant that describes the smallest amount of energy that can be emitted in the form of electromagnetic radiation.

Planck's constant (\( h \) ) is valued at \( 6.626 \times 10^{-34} \text{ J} \cdot \text{s} \). This very tiny number signifies the small energy levels associated with individual photons.

When calculating radio wave photon energy, Planck's constant allows us to understand the link between frequency and energy. Energy increases with frequency, as expressed in the formula \( E = h \cdot f \). Thus, even though radio photons have very low energy compared to visible light, they can still be quantified and calculated using this constant.
Photon Energy Calculation
Calculating the energy of a photon involves using both the frequency of the wave and Planck's constant. An important feature of this calculation is that it quantifies how much energy is carried by a photon of a particular frequency.

The formula used is \( E = h \cdot f \), where \( E \) is the energy, \( h \) is Planck's constant, and \( f \) is the frequency.

In our example, with a frequency of 1120 kilohertz, or 1120,000 Hz, we substitute into the formula: \( E = 6.626 \times 10^{-34} \cdot 1120 \times 10^3 \). This equates to approximately \( 7.42512 \times 10^{-28} \text{ joules} \).

This calculation shows how even waves with lower energy than visible light can still be accounted for and analyzed.

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