Will electromagnetic waves pass though walls that light can't?

Answer 1

First of all ... light is electromagnetic waves. But we think we understand what you're asking ...
Can longer or shorter electromagnetic waves get in where light can't ?

Here's a 'thought experiment' that can answer that question:

1). Can you listen to your radio down in a dark part of your basement where there's no sunlight?

2). Can the x-ray machine at the airport check items inside your suitcase or briefcase ?

(Here's a small hint: The answer to both questions is 'Yes'.)