Learn Unit 2-Current Electricity with Free Lessons & Tips

According to Ohm's Law, the current passing through a conductor is directly proportional to the voltage applied across it.

3. Drift velocity of charge carriers in a conductor is the average velocity with which free electrons or charge carriers move in response to an applied electric field. The relationship between drift velocity (v_d) and current (I) flowing through a conductor is given by Ohm's law: I=n⋅A⋅vd⋅qI=n⋅A⋅vd⋅q where:

• nn is the number density of charge carriers,
• AA is the cross-sectional area of the conductor,
• qq is the charge of each carrier.

• Electrical conductivity of a metallic wire is a measure of its ability to conduct electric current. It is defined as the reciprocal of resistivity (ρ) and is denoted by the symbol σ. The SI unit of electrical conductivity is Siemens per meter (S/m).

• Mobility of charge carriers in a conductor refers to the ease with which charge carriers (such as electrons in metals) move in response to an electric field. It is defined as the ratio of drift velocity to the applied electric field and is denoted by the symbol μ. The SI unit of mobility is meters squared per volt-second (m^2/Vs).

The relation between current (I) and drift velocity (v_d) of electrons in a conductor is given by Ohm's law: I=n⋅A⋅vd⋅qI=n⋅A⋅vd⋅q When the temperature of a conductor rises, the lattice vibrations increase, leading to more frequent collisions between free electrons and lattice ions. This increased collision frequency impedes the motion of electrons, resulting in a decrease in drift velocity and an increase in resistance.

• When electrons drift in a metal from lower to higher potential, it does not mean that all the free electrons of the metal are moving in the same direction. In reality, electrons move randomly due to thermal motion, but on average, there is a net movement of electrons in the direction of the electric field.

If two wires of equal length have the same resistance, the thicker wire (larger cross-sectional area) will be the one made of manganin. This is because resistance is inversely proportional to the cross-sectional area of the wire, according to the formula: R=ρ⋅LAR=ρ⋅AL, where RR is resistance, ρρ is resistivity, LL is length, and AA is cross-sectional area.