Physics - Earthing Process

bonkysleuth SG

Was doing some questions on earthing from my assessment. Here are some points I do not understand.

During earthing, do the electrons flow UP to object FROM earth or do electrons flow DOWN from object TO earth? I understand that both cases are possible. But why is it that when books ask questions about earthing, they sometimes say the electrons flow up. Other times, the explanation given for other question would be the electrons flow down. How do I know when electron from to or fro earth? Please explain. thanks

bonkysleuth SG

Oh yeah, just another question.

What is the final effect on a neutral conducting sphere after it has undergone the following procedure?

1 Place a negatively charged insulator near conducting sphere

2 Touch the conducting sphere with a finger

3 Remove the negatively charged insulator

4 Remove the finger from conducting sphere

The answer: conducting sphere becomes neutral.

I understand this concept. However, why is it that some questions tell us that for a insulating object (such as a light insulating ball), when it touches (eg. a positively charged plate) it will remain there as the -ve charges nearer to the +vely charged plate would not be transferred unlike the cases whereby a conducting ball is used.

So shouldn't the actionof placing a -ve charged INSULATOR near the conducting sphere have no effect on the sphere at all since no electrons can be transferred from the insulator?

yiha093 SG

Was doing some questions on earthing from my assessment. Here are some points I do not understand.

depends on the P.D betweem ground and object.

but normally is object to earth more common.

* based on sec 4* correct if wrong please =x

yiha093 SG

can u rephrase ur 2nd qn ?

i believe what u mean is that placing the neg insulator near conducting sphere useless ? . actually have i believe, it can repel neg charges in the sphere to the most end of sphere. this is just a trick qn i believe, if 3 and 4 were switched, the sphhere would be positive instead ?

eagle SG

Was doing some questions on earthing from my assessment. Here are some points I do not understand.

If you are negatively charged (means more electrons than normal), then electrons flow from you to earth

If you are positively charged (means less electrons than normal), then electrons flow from earth to you.

eagle SG

Oh yeah, just another question.

What is the final effect on a neutral conducting sphere after it has undergone the following procedure?

1 Place a negatively charged insulator near conducting sphere

2 Touch the conducting sphere with a finger

3 Remove the negatively charged insulator

4 Remove the finger from conducting sphere

The answer: conducting sphere becomes neutral.

So shouldn't the actionof placing a -ve charged INSULATOR near the conducting sphere have no effect on the sphere at all since no electrons can be transferred from the insulator?

I think you better rephrase your question..... -.-"