# Types of electric charges – problems and solutions

1. Based on the figure of the electric charges below.

Objects A and D are negatively charged (-), object A attract object B and repels object C, object D repels E. Determine type of electric charge of object B, C, and E.

A. Positive, Positive, Negative

B. Negative, Negative, Positive

C. Positive, Negative, Negative

D. Positive, Negative, Positive

Solution :

The electric charge consists of two types: positive electric charge and negative electric charge. Each type of charge repels the same type but attracts the opposite type. That is: unlike charges attract; like charges repel.

If charge A is a positive charge, charge A repels charge B, then the charge B is a positive charge. If charge P is a negative charge, charge P attract charge Q, then the charge Q is a positive charge.

__A is a negative charge.__

__D is a negative charge.__

A attract B so that __B is a positive charge__.

A repels C so that __C is a negative charge__.

D repels E so that __E is a negative charge__.

Types of charges B, C, and E is positive, negative, negative.

The correct answer is C.

2.

If the glass is rubbed with a silk, the correct explanation in the following table is …

Solution

Glass has a positive charge, so if the glass is rubbed with a silk cloth then the electrons move from the glass to the silk, so the glass has more protons than the electrons.

Protons are positively charged therefore glass becomes positively charged. Instead, silk has more electrons than protons. The electrons are negatively charged so that the silk fabric becomes negatively charged.

The correct answer is A.

3. Plastic rod rubbed with wool, the correct explanation is…..

A. Electrons in the wool move to plastic, plastic negatively charged

B. Electrons in the plastic move to wool, wool negatively charged

C. Electrons in the wool move to plastic exchanging with protons, wool negatively charged

D. Electrons in the plastic move to wool and exchange with protons, plastics positively charged

Solution :

The electrical charge on plastics is internationally agreed as a negative charge.

Plastic or any object becomes negatively charged due to excessive electrons. Because the plastic is rubbed with wool it is concluded that electrons move from wool to plastic.

The correct answer is A.

4. There is a ball P conductor with negatively charged and four balls of Q, R, S, T.

Ball P attract Q and repels S. Ball Q repels R and ball S repels T. If ball P brought closer to ball R and ball T then…..

Solution

P attract Q so that __Q ____is a positive charge__

P repels S so that __S ____is a negative charge__

Q repels R so that __R ____is a positive charge__

S repels T so that __T ____is a negative charge__

If ball P brought close to ball R then they attract each other*.*

If ball P brought close to ball T then they repel each other.

The correct answer is D.