# Which fundamental force is behind friction?

In day to day life we come across situations where friction is used. What is the fundamental force behind friction. For eg. which is the force behind interlocked objects like nut and bolt, which is the force behind holding an object.

If you can explain other similar practical situation in terms of fundamental forces it is very appreciated.

• Electromagnetic interaction. – Diracology Jun 16 '16 at 2:48
• Its the electromagnetic force. The 2 bodies between which there is some friction always have some irregularities on their surface. They are never perfectly smooth. To understand, we say that these irregularities fit in each other. Actually due to these irregularities the distance on atomic scale decreases and the electromagnetic force increases thereby giving rise to friction. If we smoothen the surfaces , the friction will decrease till a certain point. After which the friction increases incredibly. Think why – Shashaank Jun 16 '16 at 3:44
• But atoms are generally neutral then how is there an electromagnetic force acting at atomic level between atoms. – Shivanshu Kant Prasad Jun 16 '16 at 5:40
• What does it mean for two objects to touch? – RedGrittyBrick Jun 16 '16 at 9:23
• Not exactly a duplicate, but see my answer to How is frictional force dependent on normal reaction? – John Rennie Jun 16 '16 at 10:48