Daniel R. Faust 
Gravitational, Magnetic, and Electric Forces: Examining Interactions [PDF ebook] 

Why do objects fall toward the ground? What makes electric lights go on when we flip a switch? How do magnets work? The answers to these questions and many more become clear when you understand how electromagnetic force and gravitational force operate. This book looks at these forces and presents key concepts in an accessible way. Important theories and applications are presented in simple, age-appropriate language. Full-color photographs and primary sources provide readers with additional information.