To achieve flatness

To achieve roundness

To improve surface finish

To obtain very smooth reflective surface

Material

Length

Width

Number of teeth

Not to rub finger over file

Not to rub finger over the work piece

To apply equal pressure on file

To support file properly

It will wipe off easily

The line will be too wide for accurate work

The line will smudge and difficult to see

The lines will remain on metal even after good rubbing

More

Less

Same

None of these