Name ______
Date ______
Science Chapter 8 (B) Study Guide:KEY
Motion and Forces
Complete each statement with the correct term from the chapter.
1. The measure that shows the strength of a power source is _VOLTAGE.
2. The area of magnetic force around a magnet is its __MAGNETIC FIELD_.
3. Metals such as copper and silver are good __CONDUCTORS____.
4. A _SERIES CIRCUIT_ has only one path for electric current to follow.
5. Electric current flows along several paths in a __PARALLEL CIRCUIT__ .
6. The vibrations of a __DIAPHRAGM____turn electrical energy into sound.
7. Rubbing two objects together builds up _STATIC ELECTRICITY__ .
8. When the south poles of two magnets are brought together, the magnets _REPEL_each other.
9. A coil of wire wrapped around an iron core can act as a(n) _ELECTROMAGNET.
10. Substances with high _RESISTANCE__do not let electric current flow.
11. A short circuit results when a current uses a path of very little _RESISTANCE__.
12. Lightning is an example of what type of electicity? _STATIC ELECTRICITY._
13. A compass uses _EARTH’S_ _MAGNETIC_ _FIELD_ to give direction.
14. Earth is a giant ___MAGNET___.
15. The needle of a compass is a __THIN__ _MAGNET____.
16. A material is neutrally charged when it has equal number of _POSITIVE__ and __NEGATIVE__ charges.
17. The electrical outlets in most homes are connected in a(n)
_PARALLEL_ circuit.
18.How are a series and parallel circuit similar? BOTH CIRCUITS HAVE THE SAME PARTS: POWER SOURCE, CONNECTING WIRES, A LOAD, AND A SWITCH. BOTH CAN HAVE SEVERAL LOADS CONNECTED.
How are a parallel and series circuit different?
IN A SERIES CIRCUIT, ALL THE ELECTIC CURRENT FLOWS ON ONLY ONE PATH. IF ONE OF THE LOADS BREAKS THE CIRCUIT, THE OTHER LOADS WILL NOT RECEIVE POWER.
IN A PARALLEL CIRCUIT THE ELECTRIC CURRENT HAS A SEPARATE PATH FOR EACH LOAD. IF ONE LOAD BREAKS THE CIRCUIT, OTHER LOADS WILL CONTINUE TO RECIEVE POWER.
19.) Why is a balloon attracted to the wall? Why does it fall off later? THE NEGATIVE CHARGES ON THE BALLOON ATTRACT THE POSITIVE CHARGES IN THE WALL AND REPEL THE NEGATIVE CHARGES. THIS CAUSES THE BALLOON TO STICK TO THE WALL. AFTER THE NEATIVE CHARGES ON THE BALLOON MOVE INTO THE WALL, IT IS NO LONGER CHARGED. THE BALLOON FALLS TO THE FLOOR.
Complete the table:
Balloon’s charge / Wall’s chargeBalloon is inflated / Neutral / Neutral
Rubbed with wool / NEGATIVE / NEUTRAL
Balloon attracted to wall / Negative / Positive charges move to the wall’s surface
Ballon falls off wall / NEUTRAL / NEUTRAL
20.Describe the potential dangers of unsafe practices with electricity. What are some practices to avoid?
POTENTIAL DANGERS OF UNSAFE USE OF ELECTRICITY INCLUDE ELECTRIC SHOCK OR ELECTRICAL FIRES. EXAMPLES OF UNSAFE PRACTICES INCLUDE PUTTING TOO MANY PIECES OF EQUIPMENT ON A CIRCUIT AND USING FRAYED WIRES.
21.How are a speaker and a microphone similar? How are they different?
A MICROPHONE AND A SPEAKER BOTH WORK WITH SOUND AND ELECTRICAL ENERGY AND HAVE WIRE COILS, MAGNETS, AND A DIAPHRAGM. THEY ARE DIFFERENT BECAUSE THEY WORK IN OPPOSITE WAYS. A MICROPHONE CHANGES SOUND INTO ELECTRICAL ENERGY. A SPEAKER CHANGES ELECTRICAL ENERGY INTO SOUND.
22.You hypothesize that there is a relationship between voltage and an electromagnet’s strength. Describe how you would test your hypothesis?
START BY WRAPPING WIRE AROUND A IRON BAR TO MAKE AN ELECTROMAGNET. THEN CONNECT THE ENDS OF THE WIRE TO A BATTERY.
COUNT HOW MANY PAPER CLIPS THE ELECTROMAGNET ATTRACTED. CONNECT A SECOND BATTERY TO THE CIRCUIT. AFAIN, COUNT HOW MANY PAPER CLIPS THE ELECTROMAGNET ATTRACTED AND COMPARE IT TO MY FIRST RESULT. A 3RD AND 4TH BATTERY COULD BE CONNECTED. EACH TIME COUNT THE CLIPS ATTRACTED.