When to use は as a topic marker instead of わ?


I just learned that は is pronounced the same as わ ("wa"), instead of "ha" when
it's used as a topic marker. But I couldn't properly find information about
the grammatical rules in place to decide when to write わ or は in sentences.
Could anyone explain to me when should I use one or the other?

I believe the example below is correctly using は, but why?

> お母{かあ}さんの車{くるま} **は** それです。

Thanks in advance.

* * *

PS.: I just noticed after the first answer that I got really confused when I
was studying the subject, people don't use わ as a topic marker in sentences.
But it seems that it's too late and now I'm not allowed to delete the question
anymore.




The topic marker is always written as は and always pronounced as わ. There
isn't a case where you'd _write_ the topic marker as わ.




The topic marker is always written as は and always pronounced as わ. There
isn't a case where you'd _write_ the topic marker as わ.

