Open textbook on physics class 8 to chapter "Electrical phenomena".This led, in particular, the electrical phenomena are considered in the electric circuit.As is known, an electric current - it is directed movement of free carriers in the chain.These charges are usually electrons.Accordingly, the strength of the electric current is defined as the amount of charge passing through the cross-section per unit time.Thus, the more charge will flow in the conductor, the greater will be the strength of the current.And also, the higher the speed of movement of the charges, the higher will be the current in the resistor.
Remember that involves a concept of the resistor.In this case, a resistor should be understood any conductor or an electric circuit element having an active resistive resistance.Now it is i
mportant to ask about how the change in the resistance value to the value of current and from which it depends.The essence of the phenomenon of resistance is that the atoms of the substance of the resistor form a kind of barrier for the passage of electric charges.The higher the resistance of the substance, the more densely located the atoms in the lattice of the resistive material.This pattern explains the Ohm's law for subcircuit.As is known, Ohm's law for subcircuit is as follows: the current on the circuit voltage is directly proportional to the area and inversely proportional to the resistance of the current loop.
Draw on paper a graph of the current strength of the voltage across the resistor, as well as its resistance on the basis of Ohm's law.You will receive a schedule of hyperbole in the first case and the schedule straight in the second case.Thus, current will be greater the higher the voltage across the resistor and the smaller the resistance.Moreover, the dependence of the resistance is brighter because it has a kind of hyperbole.
Note that the resistance of the resistor also changes with temperature.If the heat resistive element and watch while the change in current, it can be seen as the temperature decreases with increasing current.This pattern results from the fact that with increasing temperature increase fluctuation of the atoms in the crystalline lattice points of the resistor, thereby reducing the space for the passage of charged particles.Another reason for reducing the current in this case is the fact that an increase in temperature of the material is increased random movement of particles including charged.Thus, the free movement of the particles in the resistor becomes increasingly erratic than aimed at, which affects the reduction current.