A point charge Q is inside a cavity in an uncharged conductor. Is the force on Q necessarily zero?
The explanation in the answer goes as
No. For example, if it is very close to the wall, it will induce a charge of the opposite sign on the wall, and it will be attracted.
This sounds weird to me because:-
First of all, it says if Q is very close to the wall, it will induce a charge of the opposite sign on the wall but opposite sign shall develop every time on the inner surface of cavity irrespective of the particle's position inside the cavity.
Isn't it that getting attracted would signify experiencing a force because of charge's own field since the field inside the cavity is just because of the charge placed [BY GAUSS LAW].