For example an electromagnet but it should be of smaller size that is the thing which undergoes the expansion or contraction should be around only 3 cm.The expansion and contraction force should be to a greater extent such that it shud be able to switch on or off a switch.The external...
For example an electromagnet but it should be of smaller size that is the thing which undergoes the expansion or contraction should be around only 3 cm.The expansion and contraction force should be to a greater extent such that it shud be able to switch on or off a switch.The external...
