Question about waves, maybe diffraction related

[fluidistic]

I don't know why my intuition tells me that generally if a monochromatic wave goes toward an aperture smaller than its wavelength (or half its wavelength maybe), the wave can't go through the aperture. Is it true?
I don't think so now... I see no reason why it would be true. And we couldn't listen to radio inside any building...
I'd like a confirmation, thank you.

 

[tan99]

Remember, it's the wavelength, not the amplitude of the light wave...
If the aperture is smaller than the wavelength, there would be maximum diffraction - the central bright fringe would fill the entire screen!

 

[fluidistic]

Remember, it's the wavelength, not the amplitude of the light wave...
If the aperture is smaller than the wavelength, there would be maximum diffraction - the central bright fringe would fill the entire screen!

Hmm? I never wrote "amplitude" and I did use "wavelength".
So you're saying that if I send a radio wave (for example wavelength around 10 km) through a 500 nm width slit, the wave would pass through the slit?