Vikas,
You want to play around with the \setbeamerfont command.
Check out, in particular, section 18.3.3 entitled "Setting Beamer's Fonts"
- You can direct commands for the whole document at various "parts" of the Beamer doc
--- \setbeamerfont {title}{size=\large} (or \LARGE or \Huge, for example)
--- \setbeamerfont {frametitle}
--- Scan the manual for all the part names you can fiddle with but for sure these are frametitle (title on each slide), title (title on the first slide), author (author's name on first slide), footer/header (the stuff at the bottom/top of each slide)... and probably subtitle? I forget all of them and haven't found a great concise list yet...
- You can also set up custom font names like this from page 199
/--------
| \setbeamerfont{parent A}{size=\large}
| \setbeamerfont{parent B}{series=\bfseries}
| \setbeamerfont{child}{parent={parent A, parent B},size=\small}
| \normalfont
| This text is in a normal font.
| \usebeamerfont{parent A}
| This text is large.
| \usebeamerfont{parent B}
| This text is large and bold.
| \usebeamerfont{parent B}
| This text is still large and bold.
| \usebeamerfont*{parent B}
| This text is only bold, but not large.
| \usebeamerfont{child}
| This text is small and bold.
\---------
Also, see secion 18.2.1 entitled "Choosing a Font Size for Normal Text"
- Essentially you set body text via \documentclass[size-goes-here(e.g. 8pt, 11pt, etc.] ]{beamer}