# Conestoga Physical Science Chapter 7

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Study guide for chapter 7 test. (Electricity)

### What is intra-cloud lightning?

lightning that occurs between the charged areas of two clouds, rther than one cloud and the ground. This happens 10 times moe often than cloud to ground lightning.

### Why does a spark jump from your hand to the doorknob as you reach for the door after walking across a carpeted floor?

Your skin and the metal doorknob are conductors, so as you walk, electrons on your shoes repel each other, electrons spread out over your skin to your hand and jump a spark to the knob.

### Explain why clothes stick together when they are removed from a dryer.

Some clothes lose electrons and become positively charged. Other clothes gain electrons and become negatively charged. Opposite charges attract.

### How is electric current different from static electricity?

Electric current involves the flow of charge, whereas static electricity involves the accumulation of excess charge.

### How do electrons flow in an electric circuit in terms of voltage difference?

Electrons flow from high voltage to low voltage.

### Why does current generally involve the flow of electrons, but not protons?

Protons are locked deep in the nucleus of the atom and do not move. Electrons are in the outer part of the atom and are free to move around the nucleus.

### Explain what a battery is.

Dry cells or wet cells connected in series that use a chemical reaction to create a voltage difference.

### List two materials that are conductors and two materials that are insulators.

Conductors-copper, silver, aluminum
Insulators-plastic, rubber, wood, glass

### What happens to the current in a device if the resistance of the device increases and the voltage difference stays the same?

According to Ohm's law, the current decreases.

Circuit breaker

E=P x T

P=I x V

Dry cell

### If the leaves of an electroscope spread apart, it indicates that________________________________________________________________.

the leaves of the electroscope have received a charge.

### A static discharge differs from an electric current in that a static discharge_________________________.

lasts for only a fraction of a second.

Electrical power

Parallel circuit

### Electric charge that has accumulated on an object is referred to as _______________________________.

Static electricity

Ohm

Ohm's law

Series circuit

Resistance

### The unit of ________________ is the kilowatt-hour.

Electrical Energy

Fuse

Carbon

amperes or amps

Volts

An insulator

An electroscope

Electrons

Induction.

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