Current and Charge

Charge carriers are a charged particle. Current in a circuit is induced by the flow of these charge carriers. Current is defined as the rate of flow of charged particles in a wire or component.

In a metal the charge carrier is an electron which is free to move around the molecule colliding with each other and positive ions within the metal.

In a salt solution the charge carrier is a ion, an ion is a charged atom or molecule.

Convention of current

Originally before the discovery of electrons it was believed that current flowed from positive to negative within the circuit, when in fact its negative to positive. (This is because electrons are negative being repelled by the negative side and attracted to the positive side of the cell/battery.)

∆Q = I∆T

I x T = Electrons passing a point in used time

1.6x10^-19

Worked example

A) If the charge flow is 50C and the current is 10A what is the time taken for this amount of charge to pass a point in the circuit?

B) How many electrons pass through the circuit in this time?

Answers

A)

Using equation ∆Q = I∆T

Rearrange it to find time, this is done by dividing the entire equation by the value of current.

This will cancel out current from the right side and divide the value of charge on the left side of the equation. This should look like

∆Q = ∆T

I

50C / 10A = 5 seconds

B)

I x T /1.6x10^-19 = electrons passing a point per value of time

10 x 5 / 1.6 x 10 ^ -19 = 3.125 x 10^20

## Wednesday, 6 April 2011

## Tuesday, 5 April 2011

### Physics/Mechanics - How to work out tension in a light inextensible string

Okay guys, best thing to do with this is not to over complicate it so you do not get confused...

Here is a picture of a pulley with 2 attached particles of mass 4kg and 5kg, if the acceleration is 1.09 meters per second per second what is the tension?

Using either of the 2 formulas

If M = largest particle and m = smallest particle

g = gravity which is a constant = 9.8(1)

M x g - M x a = T

m x g + m x a = T

5kg x 9.8N - 5kg x 1.09 = 43.6N

4kg x 9.8N + 4kg x 1.09 = 43.6N

Here is a picture of a pulley with 2 attached particles of mass 4kg and 5kg, if the acceleration is 1.09 meters per second per second what is the tension?

Using either of the 2 formulas

If M = largest particle and m = smallest particle

g = gravity which is a constant = 9.8(1)

M x g - M x a = T

m x g + m x a = T

5kg x 9.8N - 5kg x 1.09 = 43.6N

4kg x 9.8N + 4kg x 1.09 = 43.6N

## Saturday, 2 April 2011

### Haii, maths post =]

Ever wondered how to Find the value of X ? when you have a X squared equation?

Well your in luck, i know the answer :P

There is several ways.

I'm going to tell you the method that works without fail..

There is a formula which consists of..

-b +- Squareroot b^2 - 4ac

Divided by 2a

Okay so what are these letters? If the equation is as follows

X^2 + 3x + 2

A = 1 B = 3 C = 2

There is 1 x^2 -- 3 X's -- 2 is the value of the number at the end (the Y intercept)

Plug these into the formula and you should get x = -1 or -2

There is a much faster method but this can be alot more difficult than the formula above

It is called factorising, Simply place the Equation above into 2 different brackets

This is done by having 2 sets of brackets like (x+1)(x+2)=0

that is the factorisation of the equation

Now since the whole thing has to = 0 then X+1 has to equal =, therefore x is -1 and there is the second bracket (it could be the first bracket it makes no difference) (x+2) same thing again, now what is x? X = -2 :)

But how do u factorise? well if you look at the brackets i have made, and expand them yourself you will see that x times x makes the amount of x squareds x times 1 + x times 2 = 3x and 2 x 1 = 2

you just have to figure that out yourself for each equation

An easy way of doing so is start with how many x^2 do i have? in this case 1 so there is going to be 1 x in each bracket, now you need to know the y intercept which is 2 in this case... what times to make 2? 1 and 2 so there the values you place in, these have to also add up the the middle value (the b value)

Enjoy!

Well your in luck, i know the answer :P

There is several ways.

I'm going to tell you the method that works without fail..

There is a formula which consists of..

-b +- Squareroot b^2 - 4ac

Divided by 2a

Okay so what are these letters? If the equation is as follows

X^2 + 3x + 2

A = 1 B = 3 C = 2

There is 1 x^2 -- 3 X's -- 2 is the value of the number at the end (the Y intercept)

Plug these into the formula and you should get x = -1 or -2

There is a much faster method but this can be alot more difficult than the formula above

It is called factorising, Simply place the Equation above into 2 different brackets

This is done by having 2 sets of brackets like (x+1)(x+2)=0

that is the factorisation of the equation

Now since the whole thing has to = 0 then X+1 has to equal =, therefore x is -1 and there is the second bracket (it could be the first bracket it makes no difference) (x+2) same thing again, now what is x? X = -2 :)

But how do u factorise? well if you look at the brackets i have made, and expand them yourself you will see that x times x makes the amount of x squareds x times 1 + x times 2 = 3x and 2 x 1 = 2

you just have to figure that out yourself for each equation

An easy way of doing so is start with how many x^2 do i have? in this case 1 so there is going to be 1 x in each bracket, now you need to know the y intercept which is 2 in this case... what times to make 2? 1 and 2 so there the values you place in, these have to also add up the the middle value (the b value)

Enjoy!

## Sunday, 27 March 2011

### My appoligies...

My weekend got abit more crazy than i expected... so i havent been able to blog :( i will get a new post up soon while am not suffering from alcohol! About science!!! haha :D

## Friday, 25 March 2011

### Its friday, friday..

Guna get down on fridayyyyy... Am going to a club tonight guys, what your peeps doing? Or what did you do? (if you read this after friday :P)

## Thursday, 24 March 2011

Something i enjoyed being told by a friend xD

## Tuesday, 22 March 2011

### Basic chemistry, and how many electrons do atoms have + in what shell of electons?

Hey guys, i thought i'll share abit about myself today...

I study chemistry, and thought i'd teach you a little something about chemistry :D

As you can see above there is a table, this is the periodic table... each element every discovered is shown here.

Okay what makes each element different?

Well Each element consists of protons, neatrons and electrons, protons have a positive charge and electons have a negative charge, and you guessed it neatrons are neatral :D, each element has a different number of electrons neatrons and protons :) electrons and protons are the same amount unless the atom is unbalanced in charge, i.e the atom is overall positive +1 or +2 etc etc

Here is the orbit of electrons around the nucleus, how do you know how many electrons are in each shell (the path what elecrons follow around the nucleus, each shell is abit further out than the one before) ? This is where it gets a little tricky... Each atom if its big enough its basic structure is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 - the first number shows the shell its on, the second number is the amount following this path around. If you look at the periodic table and work horizontally (left to right) first is hydrogen then its helium, the number above it is the amount of electrons in the shell so hydrogen has 1 and helium has 2. For the elements lower down, the number of the row down shows what shell its on so say its 4 down its going to be in the 4s2 4p6 4d10 area, look at ZN - Zinc it says 12 above it, so count along, 4s2, 4p6.. thats 8 of the 12, so now its 4d4. Its 4d4 because that area of the shell has 10 spaces for electrons and only 4 are left.

That is a easy way to find out how many shells there is and how far into the shell it is.

I'll post more details later about atoms and there structures later :)

what you think guys? Will accept critisism :)

## Monday, 21 March 2011

### My day...

Terrible day today, come into sixthform... attend 2 lessons of chemistry with the worst teacher in the world... learn nothing, leave with the worlds most print outs... wait all day... for another lesson of chemistry... to draw a single graph and leave to go home... 7 hours of a day, thats including dinner breaks. Come home to my dog shitting on the floor, then find out my pc had a virus.. Day doesnt get much worse on a average day..

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