Hi welcome to healthcare magic ,
Dormant means the virus is present in your liver
, but it is not causing any damage.
Anytime it may become active , multiply and damage your liver.
Yes you are contagious once you are positivee for Hepatitis B
, but the chances of spreading infection is low , when the virus is dormant.
when the virus is active your chances of infecting others is very high.
Hope i answered your question..