a.

Green and yellow

b.

Blue and red

c.

Indigo and violet

d.

Orange and red

a.

Repel each other

b.

Attract each other

c.

Both move in the same direction

d.

Have no effect on each other

a.

1.0 mm

b.

0.5 mm

c.

0.2 mm

d.

0.1 mm

a.

They are represented in magnitude only

b.

They are represented in direction only

c.

Their lines of action meet at a point

d.

Their lines of action are parallel