How do I see the emissive effect created?

tayloranderson2047

I wonder why I could not see any emissive effect on this sphere under the current set-up?

Actually, I want something like this:

So how can I achieve this?

NorthOf45

Your luminance is quite low. Change it to kcd/m^2 (1000 times brighter) or cd/cm^2 (10,000 times brighter), or another setting, and/or adjust the Luminance value. You could also try lowering Exposure Value in Render Settings (changes the whole render, not just the light).

crosswind

Luminance value is too low, give it 50K or more, and you better place a floor there otherwise  it's not really apparent with no reference or reflection. Add some Translucency as well.

Fishtales

Try turning the light that is coming from the right, causing the shadow, off.

Gordig

An environment helps to sell the luminosity. The effect you're after is demonstrated in a dark room with objects for the light to illuminate, while you're currently working in an empty void with an HDRI that is overpowering the emissive effect.