We all know the ohm's law which states that V = IR. Now lets take a simple circuit where a battery is connected to a resistor via copper conductors. If the battery is of 'V' volts then the drop in the resistor is sightly less but approximately equal to V volts. And a small tiny fraction of voltage is lost along the copper conductor too since it too has some resistance. Now, from electrostatics we know that E, Electric field = dV/dx. Since there is a huge voltage drop in the resistor and it is also a voltage gradient along its length, there exist a uniform electric field along the resistor since E=dV/dx. Also, since there is a very weak voltage gradient in the copper conductor, a very very weak electric field exist in the copper conductor. What I need to know is, how a weak electric field in the conductor can abruptly become into a strong electric field in the resistor.