Wheatstone bridge is a bridge where four resistances are used. First and second resistance are connected in series; third and fourth resistance are also connected in series. Then the first and second two combinations are connected in parallel make Wheatstone bridge.
To understand completely Biot Savart Law some important rules or laws should be known are Maxwell cork screw Law, Fleming’s right hand rule.
If current passes through a conductor it creates a magnetic field around it. The direction of the magnetic field for passing current through conductor explained by Maxwell cork screw Law & Fleming’s right hand rule.
Galvanometer is very sensitive device. Flow of huge amount current can burn galvanometer or displaces spring of it. For saving galvanometer a small value parallel resistor is connected across it and makes another way out of flowing current. Parallelly connected resistor is called shunt. Total current divides into two ways. Maximum current flows through shunt resistor due to low resistance and small amount of current flow. In this way shunt saves galvanometer from damage.
Scientist Rumford and Joule did experiment in thermodynamics. In 1847 Joule showed relation between heat and mechanical energy. He explained from his experiment when work done is converted to heat and heat is converted into work done fully. So work done and heat are proportional each other. This is the first law of thermodynamics.
The process is called reversible process which can run back reversely with the same quantity of heat goes forward process. Forward heat and work done is equal with reverse heat quantity and work done. There is no loss in reversible process.
Suppose in a football game a player always makes foul. So the other good players cannot concentrate in the game and referee also. The foul making player breaks the discipline of playing. So the total game cannot be conducted properly.
Similarly increase or decrees of oxygen level in the environment both are difficult for human being. In that two cases are disorderliness or entropy increases. Disorderliness of any system is called entropy. In other words entropy is a measure of disorderliness.