How To Get Child Product Of Configurable Product In Magento

To get child product of configrable product. Firstly we need parent product id to load product and to get child products
we need to call getUsedProducts() function to get child products.

$product = Mage::getModel('catalog/product')->load($product_id);

$childProducts = Mage::getModel('catalog/product_type_configurable')->getUsedProducts(null,$product);