Questions & Answers:

What is Digory tempted to do in Chap. 4?

Digory wanted to Strike the bell and bide the danger.

Why does he do it?

He was so curious about what happened there, and didn’t want to back with wondering what else would have happened if they’d struck the bell.

Does it seem like magic forced him to do it?

No, it seems his curiosity guided him to do that.

Are there reasons why he should (or shouldn’t) have done what he did?

Firstly, it might be something with his blood relation; secondly, Digory’s curiosity drive him to do that, he wanted to make things clear since they went so far to “the world”.