Physics - Electrostatics

bonkysleuth SG

1 Charges that are placed further apart will experience

A strong attraction B. Strong repulsion C. Weak forces D Weak Attraction

Question's quite vague so I chose the more "general" answer, C. Is it right?

2 In a parallel electric field, if the current flows from -ve to +ve plate, does this mean it has a weak electric field(although lines are closer together) than the more widely spaced lines in a plate that goes from +ve to -ve ?

I still think the more widely spaced lines have weakest electric field regardless of where the field lines start and end.

3. How do you determine the direction of an electric field?

Another quite vague question. Using a positive test charge to test the path it takes?

Lastly. what is electrostatics?

I know this is quite a lame question. Tried to google it but got lame definition like "Electrostatics is a branch of physics that deals with electric charges at rest" Eh, how to properly define it?

Do help improve my answers if possible, thanks.

ThunderFbolt SG

1. err.... like charges? unlike charges?

like charges experience weak repulsion as they are pulled further apart, vice versa for unlike.

2. E= V/d, so don't care about the electric field lines drawn and focus on the distance between the parallel plates. though if stated that the electric field lines drawn are proportional to strength of electric field, more electric field lines per area means stronger electric field.

3. direction of electric field is always from positive to negative plate/point, so ya, try with a positive charge.

electrostatics is the study of charges when they are not moving? as opposed to electrodynamics? (no idea for this one)

bonkysleuth SG

Thanks ThunderFbolt.

By the way, does anyone know how to properly explain why mobile structures (eg. Toy bird hanging on wooden support) achieve stable equilibrium with their CG below their support? I don't really know how to write the explanation.

1. How is a superconductor energy-saving?

2. Give an advantage and disadvantage of superconductors

ThunderFbolt SG

btw, superconductors are materials that have 0 resistance at all below a certain temperature. this helps during the transmission of electricity over long distances as energy is lost as heat in conventional wires. in the case of superconductors, no energy will be lost at all.

advantage: superconductors can be used in maglev trains as that means that trains can travel effortlessly over long distances.

disad: most superconductors are very expensive and usually lose their superconductivity at around boiling point of nitrogen, which means that it is also expensive to maintain their superconductivity.

are you talking about the drinking bird?

http://www.shinyshack.com/product.php?prid=211057

Istvan SG

Thanks ThunderFbolt.

1. How is a superconductor energy-saving?

2. Give an advantage and disadvantage of superconductors

The centre of mass lies on the vectors of the two forces acting on the object. The first force is of course gravity. The second force is the tension holding up the object from above or the normal force propping up the object from below?

anpanman SG

Think Bonky's answers are quite correct. I just am not sure of the "what is electrostatics" question? Why not ask the moderators?

*Knock knock, moderators please?

And ThunderFbolt

Mobile structures are something like the drinking bird you have shown... something like that.

eagle SG

what is electrostatics? I know this is quite a lame question. Tried to google it but got lame definition like "Electrostatics is a branch of physics that deals with electric charges at rest" Eh, how to properly define it?

The "lame" definition is exact.

It deals with electric charges at rest. Means charges that are not moving. Charges that are stationary.

Electric charges ===> Electro
Not moving, stationary ====> Statics
Combining gives Electrostatics

We also have physics for moving charges. Moving charges can constitute a current ;)