A positively charged glass rod attracts a suspended ball of straw. Can we conclude that the ball is negatively charged?
Answers
Good question!!
First know about charges and it's types :-
Charge:- It is a physical propertie of a substance which is developed due to excess or deexcess of electrons on an isolated system .
There are two types of charge:-
1) Positive charge:- Develops due to de excess of electrons on a body.
2) Negative charge:- Develops due to excess of electrons on a body.
Note:- Unlike charges attract each other while like charges repel each other.
Now ,Let solve your question:-
Given that a positively charged glass rod attract a ball that's means ball has developed a negative charge upon it that's why it is attracted towards glass rod.
hence,from above statement we concluded that the ball has must negative charge on it.
Answer:
No, it is not concluded that the suspended ball of straw is negatively charged it can be neutral too.
Explanation:
When positively charged glass rod is made to come near the ball of straw which is neutral. The electron clouds of the straw ball attaract toward the positively charged glass rod because unlike charges attaracts. Now, there is coloumbic force of attaraction between the two. Due to this the whole straw attaracts to the positively charged rod still being neutral. This phenomenon is called as charging by induction. It is used to charge objects like charging by contact. In this there is no need of actual contact of the charged body.
When positively charged glass rod comes near negatively charged straw ball it will attaract as unlike charges attaracts.
So, we have two possibilities that straw ball can be charged negatively as well as neutral. It is wrong to conclude that ball is only negatively charged.
So, the answer is no.