Does speed of electrons decreases when they pass through resistance? What type of energy does battery supply to electrons , as I read battery increases KE of electrons but in load if they lose it then speed will decrease and current will decrease after coming out of resistance, which means current will decrease. But current remain same in circuit ....anyone may explain?
 A: In classical theory, the free electrons are in thermal equilibrium with the atoms of the conductor, but are accelerated between collisions by an electric field. The result is a low “drift” velocity. If you had a uniform conductor with a variable resistance (perhaps associated with a variation of the density of free electrons), to maintain continuity of current flow, the field (and the drift velocity) would need to be greater in regions of low free electron density. If an increase in resistance was a result of a decrease in the mean free time between collisions (as with an increase in temperature), then an increase in field strength (and acceleration) would be needed to maintain the drift velocity.  In either case, the density of free electrons will adjust itself, giving a gradient (and resulting field) that maintains continuity of flow.
A: If the current is stationary then the charge carrier density is independent of current density. A current change is due to a change of drift velocity. Since $j = \sigma E$ and $\nabla \cdot E = \rho$ there is a small excess charge density $\rho$, but this is a small effect.
A: A cell transfers electron from high voltage (low energy) to low voltage (high energy). As a result potential energy of electron increases.
As electrons cross resistance they move from low voltage (high energy) to high voltage (low energy). So they lose potential energy.
Kinetic energy remains mostly unaffected. In any case most kinetic energy of electron comes from thermal motion which has nothing to do with current.
Draw a simple cell - resistance circuit. Mark points of high voltage and low voltage. Draw path of electrons. You will figure it out.
Please note that high voltage points are low energy points for electrons due to their negative charge. Also direction of flow of electron is opposite to direction of flow of current.
