Which of these is an example of energy transfer by radiation?
a. sand burning the soles of the feet
b. a handle of a frying pan heating up an electric stove
c. hands rubbed together to become warm
d. a surfer feeling warm as sunlight shines on her

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.