Physics General Science Test Hard Mode

Sr. #	Questions	Answers Choice
1	When a Na ion and a CI ion are placed in air a force F acts between them when they are separated by a distance of 1 cm from each other the permittivity of air and the dielectric constant of water are ε₀ and K respectively When a piece of salt is placed in water then the force between Na⁺ and CI^- ions separated by a distance of 1 cm will be	F FK/ε<sub>0</sub> F/Kε<sub>0</sub> F/K
2	Two point charges placed at distance of 20 cm in air repel each other with a certain force.When a dielectric slab of thickness 8 cm and dielectric constant K is introduced between these point charges force of interaction becomes half of its previous value Then K is approximately.	2 4 √2 1
3	A point charge Q is placed at the mid-point of a line joining two charges 4q and q. if the net force on charge q is zero. then Q must be equal to	-q +q -2q +4q
4	In a Millikan's oil drop experiment the charge on an oil drop is calculated to be 6.35 x 10-19 C. The number of excess electrons on the drop is	3.9 4 4.2 6
5	Two point charge +3μC and +8μC repel each other with a force of 40 N. if a charge of -5μC is added to each of them then the force between will become	-10N +10N +20N -20N

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