Finally i was able to get shadows on Lollipop device by adding margin to the cardview. Here is the final cardview layout :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:app="http://schemas.android.com/apk/res/com.example.myapp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<android.support.v7.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="@+id/card_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardBackgroundColor="@android:color/white"
android:foreground="?android:attr/selectableItemBackground"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginRight="@dimen/activity_horizontal_margin"
android:layout_marginTop="@dimen/padding_small"
android:layout_marginBottom="@dimen/padding_small"
app:cardCornerRadius="4dp"
app:cardElevation="4dp" >
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingTop="@dimen/activity_vertical_margin" >
<TextView
android:id="@+id/tvName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="@dimen/padding_small"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ImageView
android:id="@+id/ivPicture"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/tvName"
android:layout_centerHorizontal="true"
android:scaleType="fitCenter" />
<TextView
android:id="@+id/tvDetail"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/ivPicture"
android:layout_centerHorizontal="true"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin" />
</RelativeLayout>