Respuesta :
Answer:
Explanation:
Given wavelength = 20 mm = 20 x 10⁻³ m
The microwaves are electromagnetic waves so their velocity will be equal to
3 x 10⁸ m /s.
Now frequency of microwave = velocity / wavelength
= 3 x 10⁸ / 20 x 10⁻³ = 1.5 x 10¹⁰ = 15 x 10⁹ = 15 GHz.
Considering the definition of wavelength, frequency and the propagation speed, the correct answer is option C): The frequency of 20 mm microwaves is 15 GHz
- Wavelength
In first place, wavelength is the minimum distance between two successive points on the wave that are in the same state of vibration. In a periodic wave the wavelength is the physical distance between two points from which the wave repeats itself. It is expressed in units of length (m).
- Frequency
On the other hand, frequency is the number of vibrations that occur in a unit of time. That is, frequency is the number of repetitions per unit of time of any periodic event. Its unit is s⁻¹ or hertz (Hz).
- Propagation speed
Finally, the propagation speed is the speed with which the wave propagates in the medium, that is, it is the magnitude that measures the speed at which the wave's disturbance propagates along its displacement. Relate the wavelength (λ) and the frequency (f) inversely proportional using the following equation:
v = f×λ
- This case
In this case, you know:
- λ= 20 mm = 20×10⁻³ m
- v=3 x 10⁸ m /s (All electromagnetic waves propagate in a vacuum at a constant speed of 3 x 10⁸ m /s, the speed of light)
Replacing in the definition of propagation speed:
3 x 10⁸ m /s= f × 20×10⁻³ m
Solving:
3 x 10⁸ m /s÷20×10⁻³ m= f
1.5×10¹⁰ Hz= 15×10⁹ Hz= 15 GHz= f
Finally, the correct answer is option C): The frequency of 20 mm microwaves is 15 GHz
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