It would be 12W because: 6v is half of 12v so half of 24w would be 12w
The resistance of the cylindrical wire is
.
Here
is the resistance,
is the length of the wire and
is the area of cross section. Since the wire is cylindrical
. Rearranging the above equation,

Here
.
Substituting numerical values,

Te diameter of the wire is 
An asteroid in the asteroid belt
The distance should be 11 cm and the image will be inverted (and smaller)
I used the Lens Equation:

Where:
obj. is the distance of the object
im. is the distance of the image
f is the focal length
Your answer would be : A transmission electron microscope