On a form, value of a field depends on the selection of a data in a drop down list

On a form, value of a field depends on the selection of a data in a drop down list

In a form "Session Location" I have a single line field "Location Name" and a multi line field "Location Address". Each location has a unique address. This form allows me to record an address for any specific location.
In another form "Sessions" I have a drop down list to select the location name and a multi line field to display the corresponding address. When I select a location in the drop down list, I want the muli line field to display the corresponding address. How can I do it?
Thank you for your help.
Philippe Laboise