Answer:

Explanation:
The capacitance of a capacitor in terms of the dielectric constant, area of the plate and the distance separating the plate is given by:

Where A = Area of the plate
d = distance between the plates
dielectric constant
Case 1:
When a meta slab of thickness, a, is added between the plates of the parallel plate capacitor , the effective separation between the plates becomes d+a
Therefore the capacitance of the capacitor becomes:
.......................(1)
Case 2:
Introducing a dielectric with dielectric constant K between the plates, the capacitance of the capacitor becomes:
.........................(2)
Equating (1) and (2)

If you are talking about sound frequency you need to consider what area you are in because in a concert hall it is big and helps the sound spread but in an airplane it is the opposite.
Answer:
I'm not really sure but I think it is
four
Answer: • Visible Light, Radio Waves
• Radio - 305-m , at Arecibo, Puerto Rico
Visible Light - 10.4m Mirror, Canary Island
Explanation:
The spectral window is simply the range of frequencies that are correctly measured. It should be noted that the signals that are outside the spectral window are folded when they show up in spectrum.
The two spectral windows through which electromagnetic radiation easily reaches the surface of earth are the visible light and the radio waves.