Two colours of light which mix to make white light are called
a) primary colours
b) secondry colous
c) complementary colours
d) dye

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

small = small current large mag large current