Is the nikon 18-55mm dx lens bigger on a nikon d90?

I have a nikon d90 and have read that dx lenses on a fx camera are bigger.eg the 35mm is 52mm on a fx body is this the same with all dx lenses

You are misinformed.

The FX or DX designation of a lens only says if it can be used on FX (full frame cameras or film). Both FX and DX lenses can be used on DX cameras.

It is on DX cameras such as the D90 where lenses are "longer" as per a 1.5x factor. This however applies to all lenses, regardless of if they are DX or FX lenses. That's becase this so called crop factor comes from the camera, not from the lens.

On a D90 a 50mm lens would work like a 75mm lens would do on a FX camera. For this it does not matter if that 50mm lens is a DX or FX one, the relevant issue is that it is mounted on a DX camera.

Many get confused with crop factor. I suggest they forget they ever heard about it.

The 18-55mm lens is an 18-55mm lens on any camera, be it a film SLR, a full-frame dSLR (FX), a 1.5X crop factor dSLR (DX), a 1.6X crop factor dSLR, a 4/3 dSLR, a micro 4/3 hybrid, a bridge, a point-and-shoot or any camera whatsoever. The focal length measurement stays the same, 18-55mm.

So what's the fuss about crop factors? Comparing a frame of 35mm film (~FX) to today's more popular and affordable dSLRs, that frame of film is 1.5 or 1.6 times larger than these dSLRs' cropped (DX) digital sensors. Due to that difference, the angle of view produced by the lens becomes narrower on the crop-sensor. The focal length remains the same but the angle of view is different making objects appear nearer. So with a 1.5X D90, a 35mm lens will have an effect of (35mm x 1.5) a 52.5mm lens on a film SLR. It's just an effect. Nothing changed except the angle of view.

If you are just starting to shoot with (DX) dSLRs now (I mean this digital age) and you are not using a film SLR or full-frame (FX) dSLR, you should have nothing to worry about crop factor. What you see in a 35mm or whatever lens you have (may it be DX or FX) is what you get.

The D90 is a DX camera.

All lenses, whether they are FX or DX have an "apparent" focal length upshift on a DX body, but no upshift at all on a FX body.

This even includes using a DX lens on a FX body - but this is not recommended due to the vignetting issue (although many FX cameras have a DX mode that prevents this).

http://www.althephoto.com/concepts/crop.php