Question

science matter and energy 2nd ed.
chapter 9
test 9
emma faith cleveland 861427 9
choose the best answer and fill in the corresponding bubble. use a number - two pencil only.

1. ___ discovered that static electricity exists in two forms, positive charge and negative charge.

benjamin franklin william gilbert thales of miletus charles de coulomb

1. the ___ is the si unit of electric charge.

coulomb newton joule kappa

1. a _ charge is an excess of electrons, and a _ charge is a deficiency of electrons.

positive... negative negative... neutral negative... positive neutral... positive

1. the ___ states that opposite charges attract each other but like charges repel each other.

law of electric charges law of electric fields law of electric force inverse square law

1. if two electrically charged objects attract each other with a force of 10.0 n when they are 10.0 cm

apart, what will be the force between them when they are 5.0 cm apart?
5.0 n 20.0 n 40.0 n 100.0 n

1. which of the following statements regarding conduction is not true?

a charge imparted by conduction has the same sign as the original charge.
charging by conduction is temporary; the charge is lost when the charging object is removed.
the total charge is the same before and after any interaction.
during conduction, electrons are transferred from one object to another.

1. which of the following statements regarding induction is not true?

charging by induction involves physical contact between the charging object and the object being
charged.
charging by induction produces two charges instead of one.
the law of conservation of charge is obeyed when charging by induction.
grounding can make the charge produced by induction permanent.

1. a liquid or solution that contains ions is a(n) ___.

anion cation electrolyte plasma

1. an electroscope ___.

charges neutral objects creates lines of force
detects small electric charges measures voltage

1. which of the following statements regarding current is not true?

electrons move from one place to another because of the attraction and repulsion between
electric charges.
lightning is a form of alternating current.
direct current is used in battery - powered devices.
alternating current can be transmitted over long distances more easily than direct current can be.

Explanation:

Step1: Analyze question 5

Use Coulomb's law \(F = k\frac{q_1q_2}{r^2}\). Let \(F_1 = 10.0\ N\), \(r_1=10.0\ cm\), \(r_2 = 5.0\ cm\). Since \(k\), \(q_1\), \(q_2\) are constant, \(\frac{F_1}{F_2}=\frac{r_2^{2}}{r_1^{2}}\).

Step2: Calculate \(F_2\)

Substitute values: \(\frac{10.0}{F_2}=\frac{(5.0)^{2}}{(10.0)^{2}}\). Cross - multiply: \(10.0\times(10.0)^{2}=F_2\times(5.0)^{2}\). Then \(F_2=\frac{10.0\times100}{25}=40.0\ N\).

Answer:

1. Benjamin Franklin
2. coulomb
3. negative... positive
4. law of electric charges
5. \(40.0\ N\)
6. Charging by conduction is temporary; the charge is lost when the charging object is removed.
7. Charging by induction involves physical contact between the charging object and the object being charged.
8. electrolyte
9. detects small electric charges
10. Lightning is a form of alternating current.