光線是直射的。

If the light can bend, you will simply have no shadow. The light that you mentioned is probably referred to visible light. Since its wavelength is very short. It is almost linear since the diffraction is almost negligible. However, if your size is small enough and close to the wavelength, the diffraction of light will become more significant and the light will bend and you can see the light even behind the object. The same principle is in fact happening to our daily life. The radio frequency is also a kind of electromagnetic wave. This is the same as the visible light but radio wave has a much longer wavelength. Due to the long wavelength. The diffraction of this wave is much more significant. Even you can blocked by the building, you can still receive the signal. This is because the radio wave can diffract and you will not be blocked.

I hope the informatin can help.

光是直進性
光在均勻的介質中是沿直線傳播的，即是光是直線運行的。

所以你所講的情況係唔會出現....