Why does AM radio fade out when you are under a bridge but FM does not?
Primarily because of the wavelength. THE bridge shortens the available space for the long wave signal to travel thru, it is truncated. However, the FM wave, of much shorter wavelength, does not "notice" the bridge.
if the total current in a two-branch parrallel circuit is 500 mA AND THE RESISTIVE CURRENT IS 250 mA, what is the value of inductive current
When AM radio signals pass through objects like bridge structures, the phenomenon known as "fading" occurs. This occurs due to a phenomenon called "multipath interference." Here are the steps that explain why AM radio signals fade out under a bridge:
1. AM (Amplitude Modulation) radio signals are transmitted by varying the amplitude of the carrier wave.
2. When an AM radio wave encounters an obstacle like a bridge, it gets diffracted, encompassing both the direct path and reflected paths.
3. The reflected waves bounce off the objects surrounding the bridge, such as the ground or other structures.
4. As the direct and reflected waves combine, they create interferences known as "constructive interference" and "destructive interference."
5. Constructive interference results in signal enhancement, while destructive interference weakens or cancels out the signal.
6. AM radio signals are relatively low frequency compared to FM (Frequency Modulation) signals. Lower frequency waves, like AM signals, have a longer wavelength, making them more prone to diffraction and interference.
7. When these AM radio waves encounter the structure of a bridge, the reflections can introduce destructive interference.
8. Destructive interference causes the AM radio signal to partially or completely cancel out, resulting in a faded or weak signal when you are under the bridge.
On the other hand, FM radio signals use a different modulation technique called frequency modulation. FM signals occupy a higher frequency range compared to AM signals, which makes them less susceptible to the effects of diffraction and multipath interference.
Overall, the differences in modulation techniques and frequency range between AM and FM radio signals contribute to the phenomenon of fading under a bridge, primarily affecting AM signals.
AM radio signals tend to fade out when you are under a bridge due to a phenomenon called "multipath interference." To understand this, let's first understand the differences between AM and FM radio.
AM, or Amplitude Modulation, encodes the audio information onto the carrier wave by varying its amplitude. On the other hand, FM, or Frequency Modulation, encodes information by varying the frequency of the carrier wave.
Now, when you are under a bridge, the AM and FM signals experience different effects. AM signals are more susceptible to multipath interference because they bounce off objects and surfaces, creating multiple paths for the signal to reach your receiver. As a result, multiple copies of the signal with different amplitudes arrive at your receiver at slightly different times. These multiple copies interfere with each other, causing fading.
FM signals, on the other hand, are less prone to multipath interference. This is because with FM, the audio information is encoded in the frequency variation rather than the amplitude. When FM signals bounce off objects or surfaces, they retain their frequency modulation, allowing the receiver to distinguish between the original and reflected signals. The receiver can then use clever techniques, such as diversity reception or phase-locked loops, to eliminate or reduce the impact of multipath interference.
In summary, AM radio signals fade out under bridges due to multipath interference, while FM signals are less affected due to their encoding technique and the receiver's ability to mitigate interference.