Do flat screens TV use less electrict than the older models ?

The first generation of Plasma screens used about half the power of the old CRT televisions, but they have gotten a lot more efficient.

The old CRT televisions actually had a heating coil in the 'gun' to generate the electron beam. This created a lot of heat that was basically waste.

Modern LCD/LED flat panels are a lot bigger screen, but no heat so even though you get a bigger screen size, the power use is reduced.

They are more power efficient, so an LCD TV would use less electricity than a comparable CRT TV. However, since flatscreen TVs can be much larger (there are many flatscreen TVs that are 40"+, which is unfeasible with a CRT), it is possible that they actually use more energy.

Yes significantly! Old tube TV's were commonly 400w+ while modern LCD TVs are commonly about 1/10th that power consumption.

Yes, they are more power efficient