PHP character escape sequence does not work

I am an extreme web programming beginner who is just starting to learn PHP with some knowledge of HTML and JavaScript.

I use WAMP Server as my web server and Eclipse PDT as my IDE. I created a .php file in Eclipse. I just want to run a simple code that I pulled from a text book:

<?php
echo "Hello World\napple";
?>

However, the line break does not work and it just makes a space.

How can I solve this?