Class 12th

Resistance of whole wire is

$R=r^{\text{'}}*l$

$20=1*l$

$l=20m$

Let length of the shorter section = a

$\frac{1}{R}=\frac{1}{a}+\frac{1}{\left(20-a\right)}$

$\frac{1}{1.8}=\frac{20-a+a}{a\left(20-a\right)}?20a-a^2=36$

$a=2and18$

$?a=2m$

Here are a few factors which are not responsible for affecting the motional EMF:

• Resistance
• Temperature
• Material
• Shape and Mass
• Electron Flow

This chapter covers the concepts of potential, capacitors, and potential energy. It is considered as one of the easy chapter of the class 12 Physics.

It is the farad (F). The name came from Michael Faraday. SI Unit of Capacitance means the ability of a system to store an electric charge. One farad is the capacitance of a device that needs one coulomb of charge to provide one volt potential difference across it. Mathematically, it is represented by - 1 Farad = 1 Coulomb/Volt. 

Motional EMF is a condition which arises due to the movement of conductor in a magnetic field. On the other hand, induced EMF is a cause of change in the magnetic fiedl over a certain timespan. Induced EMF arises when there is a change in the magnetic flux.

In JEE Main Physics, electric potential and capacitance chapter has a weightage of 3% to 6%. You can expect around 1 or 2 questions from this chapter which carries 4 to 8 marks.

In NEET Physics exam, the chapter electric potential and capacitance carries a weightage of 2% to 5%, which means you can expect one question out of 45 questions.

The ability to do work on a charge is called the electric potential and the ability to store charge is termed as the capacitance.

The movement of the body in the conductor is caused by the magnetic field. This magnetic field then causes an electric current to flow in the system. Hence, the direct action is caused by the magnetic force on the object, due to which it becomes the major source of motional EMF.