Resistivity notes

Resistivity
The resistivity of a material expressed in ohm metre units is numerically equal to the
resistance of a conducter of the materail of length 1 metre and of cross sectional
area 1 metre squared.
Fardays law of electromagnetic inductiom
Whenever there is a change in the magnetic flux linked with a circuit an electromagnetic
force is induced, the strength of which is proportional to the rate of change of the
flux linked with the circuit.
Lenzs law of electromagnetic induction
The direction of the induced current is always such as to oppose the change producing
it.
Mass number
The total number of protons and neutrons in a nucleus is called the mass number and is
denoted by A.
Atomic number
The atomic number is defined as the nimber of protons in a nucleus and. is denoted by Z,
Isotopes
Isotppes of an element are atoms which have the same atomic number but different mass
numbers.
When an element disintegrates by the emission of an alph particle it turns into an
element with chemical properties similar to those of an element two paces earlier in
the periodic table.
When an element disintegrates by the emission of a 1'ata particle it turns into an elemen
with similar properties to that of an element one p3 ace later in the periodic table