.electromotive-force1{width:220px; height:171px ;}
.electromotive-force2{width:173px; height:241px ;}
.emf-example1{width:114px; height:87px ;}
.emf-formula{width:123px; height:187px ;}
.battery{width:126px; height:66px ;}
.emf-example2{width:148px; height:92px ;}
.emf-calculate{width:114px; height:229px ;}
.emf-example3{width:126px; height:101px ;}
.emf-example4{width:183px; height:48px ;}