 So we have found the drift velocity. Why we have found? You have cross section of area A. Okay. Electrons are supposed to be moving like this with drift velocity. Charge is E, number volume is small n. Okay. Give the motion of charge. So we need to find out in one second how much charge will cross this area. So in one second how we can do tau. Okay. E squared capital E. So there are two E's. Oh sorry. This is. Microfactors. Now does that expression make sense? If mass is small, should resistivity be electron? Okay. Then into 10 small 3, 1.1 into 10 to the power minus 3, 1 meter per second and see how understanding about resistance. Fine. Do you know the relation between resistance entrance towards it? Right. So if you take, but increase the area. What? There will be more movement. There will be more movement. There will be more charge difference. Okay. So since current decrease. Fine. So resistance should be inverse. So R is proportional to the constant itself and that is rho.