Personal Computer or Laptop
Physlets require Java to run. Java runs on personal computers and laptops but not tablet-based devices. Do you have Java already installed? To check on a Windows-based machine, open the Control Panel and look for the Java icon. To check on a Macintosh computer, open the System Preferences, and look for the Java icon at the bottom of the panel.
Browsers and Operating Systems
Getting Oracle Java
Java is available for free from Oracle. The Java Runtime Environment (Standard Edition) can be downloaded from the Oracle website: Oracle Java SE Runtime Environment 7 Download Page. After accepting the license agreement, choose your operating system and download the file to your hard drive. Double-click on the file's icon to run the installer. Follow the instructions the installer provides. If you have a 32-bit browser, select 32-bit Java. If you have a 64-bit browser, select 64-bit Java. If you use both browser types, download and install both versions of Java. To test that your browser can run java applets, go to http://java.com/en/download/installed.jsp
Note: After a recent Java update, some Microsoft Windows computers cannot run java applets in any browser. This is related to java being installed in a directory with a space in the name, such as "Program Files (x86)". If you are having this problem, you should try installing the update in a different directory, such as "C:\java", by checking the "Change Destination Folder" box on the first installation page.
Mozilla Firefox and Google Chrome offer alternatives to Microsoft Internet Explorer on Windows operating systems.
Mozilla Firefox offers an alternative to the Safari browser on the Macintosh. Because the latest version of Java on the Macintosh is 64-bit Java and Google Chrome is currently a 32-bit browser, Chrome on the Macintosh is incompatible with Java 7. Google Chrome will run Java applets if the Macintosh computer or laptop has the original 32-bit Java from Apple installed.