on depending on or positive spontaneously d) The charged discharges anging on 9

Question

on depending on or positive spontaneously d) The charged discharges anging on 9 A person rubs a neutral comb through their hair and the comb becomes negatively charged. Which of the following is the best explanation for this omenon? a) The hair gains protons from the comb. b) The hair gains from the while comb giving electrons to the s the two spheres c) The hair loses electrons to the comb. d) The comb loses protons to the person's hand while also gaining electrons from the hair. When a negatively charged rod is brought near, but does not touch, the initially uncharged electroscope shown above, the leaves spring apart When the electroscope is then touched with a finger, the leaves collapse (ID. When next the finger and finally the rod are removed, the leaves spring apart a second time (I). The charge on the leaves is a) positive in both I and III negative in both I and III c) positive in L negative in Ill d) negative in l, positive in III

Explanation / Answer

9) when two objects are rubbed against each other, one becomes positively charged and the other object is negatively charged.
Materials are normally electrically neutral as they have equal number of electrons and protons.When two materials and rubbed against one another,electrons move from one material to another. As a result, one of the objects acquire positive charge and the other acquires a negative charge.This is the cause of static electricity.
So option (c) is correct.
The hair losses electron to the comb.As a result the hair accquires a positive charge.

10)An electroscope is used to detect even feeble charges.Detection of the presence of charge can be done in two ways i.e. by touching the body and without touching the body.

Now, when a negatively charged rod is brought,the leaves spring apart.So, we can conclude that the leaf is negatively charged. This is because the negatively charged body repels the electrons of the plate and the leaf.The negative charge in the plate and leaf increases and hence divergence increases.When the electroscope is touched with fingers the leaf collapses because on touching the cap,the free eletrons cannot flow to the earth as they are bound .The leaf system becomes neutral.Hence,the leaf collapses.

when finally both the finger and the rod are removed,the leaf shows divergence due to repulsion between the like charges.

so, option (d) is correct.

12)The direction of electric force due to positive charge is in the outward direction.Also the electrostatic force is dependent on the magnitude of charge i.e. greater the charge more is the electrostatic force.So,option (c) is correct.

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