Because they aren't better than active 3D television.
Both have their advantages. Passive televisions use polarizing glasses to separate the left and right eyes' images. The effect is that the perceived resolution is cut in half to 540 lines, less than the 576 lines of older standard definition images.
An active filter can provide much sharper band-edge characteristics than a passive one, with the same or smaller number of components, cheaper, and without the through-loss of a passive filter.
Active voice is much better than passive voice in writing.
Active 3D glasses are far better than passive glasses when used with an active 3D television. Similarly, passive 3D glasses work well with passive televisions. Active glasses have been criticized for their weight in the past. Later glasses are lighter than many passive glasses, have a battery life of over one hundred hours and are proving to be exceptionally reliable.
Passive glasses are lighter, and a little cheaper than active glasses. Passive glasses are under £10 whereas active glasses start at a little over $10. Passive glasses need no batteries but the resolution of passive 3D such as LG is half that of other 3D systems at just 540 lines, lower than the standard definition of 576 lines that was introduced almost 50 years ago.
Active mic usually has battery in it and gives way better sound recording quality than passive one. This is smart microphone if you will and I'd recomment to stick with active if you're doing audio recording or movie at home.
yes
Passive Hubs These hubs are nothing more than point contacts for the wires that make up the physical network. An example of this would be a punchdown block that is a simple plastic, unpowered box used to plug network cables into it. Active Hubs Active hubs are a little smarter than the passive hubs we saw. All You might also come across the term "concentrators" which are basically active hubs, concentrating and strengthening a signal as it enters and exits the hub.
Active systems have a much longer range than passive systems due to having an internal battery. Because of this an active tag will be much larger and more expensive than a passive tag. The passive tag will basically convert the RF signal from the Interrogator or reader and turn it into energy to return the signal. Active tags will often be found on larger sized shipping containers/products whereas a passive tag, due to its small form factor can be used on any variety of products, containers, boxes...etc. Passive tags are usually more durable than active tags. While some active tag batteries have a lifetime of 10 years, depending on the frequency of use, passive tags do not have the handicap of internal power requirements. Depending on the harshness of the environment, an industrial grade passive Read-Only tag can last longer than your average person.
Active transport requires the cell to expend energy. However passive transport occurs because of a gardient.
What do you mean, what do I mean? Did I use the expression "active and passive voice"? I don't think so. No, you want to phrase your question "What is meant by the active and passive voice?", because that way you don't have to say who is using those words. You see, normally if you say something like "B. King is discussing active and passive voices" you have to say that it is B. King that is doing it, but if you don't know or don't want to say, you can turn it around backwards so it says, "Active and passive voices are being discussed." There. You don't know from that who is discussing it, do you? Perhaps you would like to know what this turning around backwards is called? It's called the passive voice. Yes, I asked you to rephrase your question so it was in the passive voice ("What is meant by the active and passive voice?") rather than the active voice ("What do you mean by active and passive voice?").
Passive (just guessing)
Active. He Did Something, rather than Something Happened To Him.