2. Resistance :-- Resistance is a measure of the opposition to current flow in an
electrical circuit.
Resistance is measured in ohms, symbolized by the Greek letter omega (Ω).
Ohms are named after Georg Simon Ohm (1784-1854), a German physicist who
studied the relationship between voltage, current and resistance.
R = l / A
The resistance (R) of a material depends on its
•length
•cross-sectional area
•the resistivity
3. Resistance Box
Definition:-- The box which contains the resistors of different values for
estimating and comparing the resistance is known as the resistance box.
The accuracy of the resistance box is very high.
The main application of the resistance box is to control the specific value of
current to flow through the circuit.
The main advantage of the resistance box is that the variable
resistances are available at one point.
If any circuit requires variable resistances, then there is no need of
replacing the resistor.
The resistance box is of three types.
•High resistance Box :-- value of the high resistance box lies from 1Ω
to 5000Ω .
•Low Resistance box :-- value of the low resistance box is between 1
to 500Ω.
•Fractional Resistance Box :-- value of resistance is in the form of a
fraction. The range of fractional box lies between 0.1Ω to 50Ω.
4. And current always take the path of least resistance.
In this picture yellowish color metal is made up of Brass & it has more cross
section area then it offered low resistance that’s why most of the current flows
through the brass material when no plug is out from resistance box.
when you plug out the any plug
Let say 1 & 2 ohm
5. then current will flow through the resistance 1 & resistance 2 and then through
the brass material.
(Internal Structure of resistance box )
