Example – 1 A Solid metallic sphere is placed in a uniform electric field. Which of the lines A, B,
C and D shows the correct path and why ?
Solution : Path (A) is wrong as lines of force do not start or end normally on the surface of a conductor. Path (B) and (C) are wrong as lines of force should not exist inside a conductor. Also lines of froce are not normal to the surface of conductor. Path (D) represents the correct situation as here line of force does not exist inside the conductor and starts and ends normally on its surface.
Example – 2 A metallic slab is introduced between the two plates of a charged parallel plate capacitor. Sketch the electric lines of force between the plates.
Solution : Keeping in mind the following properties :
1. Lines of force start from positive charge and end on negative charge.
2. Lines of force start and end normally on the surface of a conductor.
3. Lines of force do not exist inside a conductor (as field inside a conductor is zero)
The field lines between the plates are as shown in the figure.
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