⭕Ohm's Law:
For a Constant Temperature,
Voltage is directly proportional to Current.V=RI (R= Propertionality constant or Resistance)
Unit for R= Ohm (Ω)
▶️Ohm's Law was proposed by Gorge Simmon Ohm.

▶️ohm's law is only Applicable for Constant Temperature.
▶️Due to the heat loss ( when current is flowing some amount of heat is produced which increases heat loss)
▶️As heat loss is present , Temperature can never be constant hence Ohm's law is applicable only in " Ideal case"

🔷 According to Joule's law:
Heat loss= I² Rt

⭕ Temperature Coefficient of Resistance:
▶️1) For Conductor : 'Positive temperature coefficient'
i.e when Temperature is increased, Resistance also increased.
▶️2) For Insulator & For semiconductor : 'Negative temperature coefficient' i.e temperature increased, Resistance Decreased!

⭕Resistance:
1) Resistance directly propertional to length of conductor.
2) Resistance is inversely propertional to Area of cross section of Conductor.
R ≈ l/a , l= length (m)
a= area of Cross section(m^2)
Resistivity is a Propertionality constant ( also known as Specific Resistance)
2️⃣Unit :
Resistivity = R .(a/l )
Ω .(m^2/ m)
Unit = Ω• m

💠 Specific Resistance/ Resistivity depends upon Composition of conductor material
💠 i. e only depends upon material property & unlike Resistance it is independent of Length & area of cross section.

🔶Note:
🅰️ Conductor : R(Resistance )≈ l(length)

🅱️Insulator :
R(Resistance)≈ [1/ l( length)]

🔴When any conductor is streched by definite length then it's Area decrease at same amount of length is increased to make Volume Constant.

🔘If one Copper wire is of 10m & other Copper wire is of 50 m find it's Specific Resistance Ratio?
▶️ For a Same material wire, Specific Resistance i.e resistivity will be same for both. As resistivity depends on material ( copper used) but not on length
Hence , ratio will be 1.

🔵 Quantities:
1️⃣Current is neither a Scalar quantity nor Vector Quantity ( most of the books Prefer current as Scalar quantity)
But Current is a 'Tensor Quantity'.
2️⃣Current Density- Vector Quantity.
3️⃣Voltage- Scalar Quantity.
4️⃣Electric Field- Vector Quantity

🔴 Limitations of Ohm's law
⏩Ohm's law cannot be applied to the circuits consisting of,
1) electronic tubes or transistors ( because such elements are not bilateral)
2) Nonlinear elements such as powdered iron, electric arc ,etc

🔵If length of wire of Resistance R is uniformly stretched to 'n' times it's original value,what will be it's new Resistance R?
⏩ New Resistance
= Old Resistance× (new length/old length) × (old cross-section/new cross-section )
= R× (nl/l)× (a/a÷n)
= n^2× R

➡️The Resistance of the conductors( expect carbon) increases with increase in temp., Therefore on high temp. Good conductors become bad conductors even.
➡️ The insulators lose their insulating power with the increase in temperature and some may become good conductors if they are strongly heated.

🔴Potential divider is a high Resistance connected across the supply mains and is used to provide a variable voltage from a constant supply voltage

🔵SI units:
1) Force: Newton
2) work : newton-metres (or joules)
3) Power: newton- metre per second (or Joules per second)
4) Energy: newton-metre ( or joules)

⭕ About Turbines:
✅Classification of Turbine:
1) based on water discharge
a) High discharge - Kaplan turbine
b) Medium discharge - Francis turbine
c) low discharge - Pelton turbine

2) based on Water pressure
a) impulse pressure - Pelton turbine

b) Reaction pressure - kalpan,Francis,propeller turbines are used

3) Base on direction of water flow:
a) Axial flow - Kaplan turbine
b) radial flow - Francis turbine
c) tangetial flow - Pelton turbine
d) Diagonal flow - deriaz turbine used...!

⭕Demand factor = max. Demand / connected load

⭕Load factor = Average load/peak load

⭕ Utilization factor = max. Load/ rated plant capacity