It depends on the lens. Most smaller Nikkor lenses take 52 mm filters.
All filters are threaded to screw onto the inside threads of the outside rim of a lens. Virtually all lenses, especially those for a digital camera such as yours, will accept a screw on filter at their 'outer' rim (away from the camera). Be sure the filter you have is the same diameter as the lens - they come in varying sizes, according to the type of lens.
We cannot filter too much UV rays. This is the work of ozone in our atmosphere.
No, the visible light region is between Infra-red and UV.
Yes, it is the only thing. It filters the UV.
Ordinary glass will filter out UV rays by itself. So you will get the combined filtering of the glass and the ozone reducing the UV ray intensity.
Protection from Ultraviolet rays/sunlight
ozone layer
The ozone can filter harmful radiations. These are the UV rays of the sun.
to check the sensitivity of the instrument
A UV air filter will be helpful in your home to catch pollens and dust for those who have allergies. It keeps the air clean and for a decent sized house I would recommend a Germ Guardian.
A lot of stores offer UV protection filters. Sites such as Amazon and Bestbuy offer a variety of UV protection filters for a camera. Ebay also offers UV filters for sale.
Ozone filters out the harmful UV rays of the sun. It is important as these are fatal rays for life on earth.