Ch 11Electric Current Through Conductors — Class 11 Physics, concept-first.

When a very large number of atoms of a metal come together to form a solid, the outermost (valence) electrons of each atom no longer stay bound to their own individual atom.

To define current precisely, imagine an idealised 'gas' containing both positively and negatively charged particles, moving randomly in every direction, all of them able to cross some fixed imaginary…

A current does not require negatively charged carriers specifically -- it can, in general, be generated by the motion of positively charged particles, negatively charged particles, or both together.

Picture a copper rod with no current flowing through it (Fig. 11.2): its free electrons are in constant random thermal motion, colliding repeatedly with the fixed ion cores of the lattice, but there i…

The relationship between the current through a conductor and the potential difference applied across it was first discovered experimentally by the German scientist Georg Simon Ohm in 1828 AD, and is k…

Ohm's law can be derived from the microscopic picture of electron drift introduced in section 11.4. Electrical conduction in a metal is due to the mobile conduction electrons, assumed free to move thr…

Ohm's law is obeyed by many, but by no means all, materials and devices. Devices for which the current-versus-potential-difference (I-V) graph is a straight line passing through the origin (Fig.

Consider a resistor connected to a cell in a circuit (Fig. 11.6), with current flowing from to . The cell maintains a potential difference between the two terminals of the resistor, with at the higher…

Resistors are components deliberately placed in a circuit to LIMIT the current flowing through a particular path.

A RHEOSTAT (Fig. 11.8) is an adjustable resistor -- a resistor whose effective resistance can be varied continuously by hand -- used wherever a circuit needs the current or resistance to be adjusted i…

Just as in any electrical network, multiple resistors in a circuit can be combined together in two basic ways -- connected end-to-end along a single path (SERIES combination) or connected between the…

In a SERIES combination, resistors are connected one after another along a SINGLE electrical path (Fig.

In a PARALLEL combination, the resistors are instead connected between the SAME two electrical (junction) points, so that each resistor forms its own individual path between those points and the SAME…

At a given temperature, the resistance of a conductor is found experimentally to depend on three things: the nature (material) of the conductor, the length of the conductor, and the area of its cross-…

Resistivity is a property of a material that VARIES with temperature. Fig. 11.11 shows how the resistivity of copper varies as a function of absolute temperature (in kelvin); over a fairly wide range,…

When charge flows steadily through a conductor, a potential difference must be established -- and continuously MAINTAINED -- across the two ends (terminals) of the conductor, or the flow would simply…

In a SERIES combination of cells, the cells are connected along a single electrical path such that the POSITIVE terminal of one cell is joined to the NEGATIVE terminal of the next, and so on down the…

In a PARALLEL combination of cells, all the POSITIVE terminals of the cells are joined together at one common node, and all the NEGATIVE terminals are joined together at another common node (Fig.

Electrical cells can be broadly divided into several categories, including PRIMARY cells, SECONDARY cells, and FUEL cells.