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21 terms

Physics

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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.