Electrostatics Flashcards
When you take clothes out of the dryer right after it stops the clothes stick to your hands and arms is your body charged, if so how did it acquire a charge if not why does this happen
the clothes have friction in the dryer and the body is a conductor but the excess charge leaves right away and the body is actually is polarized because of the clothes and because of this the charges seperate enough that the positive attract the negative temporarily on clothes and even tho the body is neutral the charges seperate on the surface of the body and therefore it is polarized
A negatively charges rod is brought close to neutral prices of paper which it attracts explain why this attraction occurs
Its clear polarization, charges in insulators don’t seperate a great de also not many negative trailing to the end and they are still attractive to molecule whihc tehy are apart so local separation of charge and they will move far away as they can within the constraints of their electrical attraction to teh other nucleons in there while teh surface acts as a positive charge and attracts the rod and hangs on to it
Why does a plastic ruler that has been rubbed with hair or fur have the ability to pick up small pieces of tissue paper? The paper attracts to teh ruler initially but in short amount of time many will launch themselves from the ruler why? Why is this process difficult to do on a Humid day
Ruler has gained electrons from teh fur and has net negative charge. Charge polarizes the charger on paper drawing positive charger closer to rod and reflecting the negative charge further way. Polarization results in a net attractive force on paper so for a small amount of time a small amount of charge is able to create enough electric fore to be stronger than gravity so paper can be lifted. On a humid day there are more water molecules in the air water is polar so charges no equally distributed nad water can attract some free charges away from ruler so not enough electric force to pick it up, also there is more water in teh air on a humid day, there aren’t a lot of conduction electrons or free electrons and done on a dry day bc it’s looses charge to water in the air because water is polar
Contrast net charge on a conductor to the free charged in the conductor
net charge is excess unbalance between positive or negative charge and free charge is always there for metals valence electrons that are free to move around
When an electroscope is charged it’s two leaves repel each other and remain at an angle, what specifically balances the electric force of repulsion so that the leaves do not seperate further
Gravity pushing down adn tension combined
The form of Coulomb’s law is very similar to that for Newton’s law of universal gravitation what are the similarities and differences between these two laws
Both have a constant both have product of fundamental property- product of masses adn product of charges, inverse square, Coulomb’s has large constant Newton has small constant Coulomb’s is both attractive or repulsive Newton is attractive only– shows that mass and charge there’s only one mass and two kinds of charges no direction of mass but yes fro charge
We are not normally aware of the gravitational or electric force between two ordinary objects what is the reason in each case
Most everyday Objects electrically neutral, force of gravity is very very small and not aware of it
Is the electric force a conservative force why or why not
Yes the work done by the froce is independent of the path, same regardless of teh path taken
Explain why teh test charges we use when measuring electric fields must be small
They can’t interfere with teh field lines themesleves
Why do we use a small positive test charge when measuring an electric field some distance from a charge
By convention we had to pick one and needed consistency
Why is it that electric field lines can be closely spaced but never crossed
Vector quantities so if they did intersect they would have two directions and the net charge can only have 1 direction.
Is there a point long teh line joining an electric dipole where the net electric field would be zero if yes indicate where that would be
There is always a charge so zero because always electric field towards the negative
If q1=-.1 mC is located at the origin and q2=+.1 mC is located on teh positive x axis at x=1 m which is true about teh force on q1 due to q2, what if they are switched what is true of the forced
It is attractive nad directed in teh positives direction, it changes from teh positive x directions to teh negative x direction
Fred the lightening bug has a mass m and a charge +q and have the lightning bug wide a has a mass of 3/4m and a charge of -2q because they have the charged of opposite sign they a re attracted to each other, which is attracted more to the other and by how much
They a re attracted to each other by the same amount
As an object acquires a positive charge it’s mass usually
Decreases bc it is losing electrons
