# Physics

### 21 terms by mykim

#### Study  only

Flashcards Flashcards

Scatter Scatter

Scatter Scatter

## Create a new folder

### What part of an atom is positively charged and What part is negatively charged?

The nucleus of the atom has positive charge
The electrons in orbit have a negative charge

### How do the numbers of protons in the atomic nucleus normally compare to the numver of electrons that orbit the nucleus?

In an atom the numbers of protons + = the number of elctrons

### Why are metals good conductors both of heat and of elctricity?

because the atoms have loose outer electrons.

### Cite an example of something charged by friction.

An example of charging by friction is rubbing a balloon on your hair.

### Give two examples of common force fields.

Gravity, electric field, magnetic field.

### Why are electrons, rather than protons, the principal charge carriers in metal wire?

Electrons are the principle charge carries in wires rather than protons, becaue e- are free to leave their atoms.

### Name two kinds of Practical "electric pumps"

Batteries and Generators

### Will water flow more easily through a wide pipe or a narrow pipe? Will current flow more easily through a thick wire or a thin wire?

Water will flow more easily through a wide pipe.
Electric current flow more easily through a thick wife.

### If the Voltage impressed across a circuit is held constant while the resistance doubles, what change occurs in the current?

I=v/r, If R doubles, In 1/R I becomes less 1/2

### If the resistance of a circuit remains constant while the voltage across the circuit decreases to half its former value, what change occurs in the current?

I=V/R I~V, If voltage decreases to 1/2, current I will also decrease to 1/2

### Why is it a very poor idea to handle electrical device while in the bathtub?

You have less resistance in when wet, I~1/R
When resistance decreases, current increases.

### Distinguish between DC and IC

DC: Direct current in 1 direction only
AC: Alternating current changing direction.

### Does a battery produce DC of AC? Does the generator at a power station produce DC or AC?

A batter produce DC current.
A generator produce AC current

### From where do the electrons originate that produce an electric shock when you touch a charged conductor?

when you touched the pietin and got shocked, the electrons came from the pietin atoms.

### What is a main shortcoming of a series circuit?

The main shortcoming of a series circuit is that if 1 lamp goes out, all the other lamps go out

### Are household circuits normally wired in series or in parallel? and when are they overloaded?

Household circuits are wired in parallel

### What is the function of fuses of circuit breakers in a circuit?

Fuses or circuit breakers cut off excessive current to wires to prevent them from overheating and melting.

### What produces a magnetic field?

created by moving an electirc field

### What two kinds of rotational motion are exhibited by electrons in an atom?

An e- in an atom orbits, and spins on its axis

### At the micro level, what is the difference between an unmagnetized iron nail and a magnetized iron nail?

In an unmagnetized iron nail the atoms electrons are not aligned
In a magnetized iron anil they are aligned

### What effect does Earth's magnet field have on the intensity of cosmic rays striking the Earth's surface?

The earth's magnetic field pushes away the sun's cosimc ray.

Example: