Class 12th

$\theta = 90°$

Let V  be the potential of the junction as shown in figure. Applying junction law, we have

or $\frac{20-V}{2}+\frac{5-V}{4}\overline{\to }\frac{V-0}{2}$

or $40-2V+5-V=2V$ or $5V=45\Rightarrow V=9V$

$\therefore i_3=\frac{V}{2}=4.5A$

Please consider the following Image  

Before closing the switch

After closing the switch

So charge on C₁  remains same, on C₂ increases and on C₃ and C₄  decreases.

The sum of a magnetic field that passes through a given surface area is called the magnetic flux. The mathematic formula is? = BA cos (? ). 

Ohm's Law states that when the temperature remains constant, the current (I) flowing through a conductor is directly proportional to voltage (v), and inversely proportional to resistance (R).

As per the Faraday's Law of Induction, when a conductor is exposed to a changing magnetic field, a circulating electric current is induced, it is called the Eddy current. The Eddy currents have many applications including - non-destructive testing and induction furnaces.

The basic principle of the electromagnet is the electromagnetism. When the ferromagnetic iron core is coiled by a wire and a current is passed through the core, it produces a strong and magnetic field, and turns the setup into a magnet. By changing the current, one can change the strength of the magnetism, and when the current is switched off, the magnetism disappears.

The process of creating the electric current in a conductor by moving the conductor through the magnetic field or by changing the magnetic field around the conductor is known as the Electromagnetic Induction.

The sum of a magnetic field that passes through a given surface area is called the magnetic flux.