help in physics

[niassu]

hi, plz if anyone can explain the electric motor, genrator and the lenz law , flemings right hand rule and eddy currents????

mmm..... can u plz tell me if the oxford (complete phsics for igcse) is good enough

 

[XPFMember]

Assalamoalaikum!!

well i personally like that book!! It's nice...and if u have the latest edition of it...u'll notice it's been classified according to the syllabus!!

btw did u go through the explanation given in the book??

 

[niassu]

Assalamoalaikum!!

well i personally like that book!! It's nice...and if u have the latest edition of it...u'll notice it's been classified according to the syllabus!!

btw did u go through the explanation given in the book??

Ya dear i've got it & i've read these in them but still doubtfull so if u kindly have the book i can tell u wht i cann't get exactly so tht u could cooperate with me

 

[XPFMember]

yeah u carry on..i have that book!!

 

[niassu]

soory for being late
on page 259 i dont understand the first question.

 

[XPFMember]

soory for being late
on page 259 i dont understand the first question.

Assalamoalaikum!!
well..r u sure it's pg 259...which edition do u have..cuz on that page i have the chapter-radioactive decay!...u till me a little bit of the question..i'm sure the questions will be the same!!

sorry 4 the inconvenience!

 

[niassu]

wa allaikm el salam
me too have the radioactvity(2) imean the the questions ion the end of the page which is about
(If samples of strotium-90 and radium-226 both had the same activity today,which would have ythe lower activity in 10 years'time?????
thnx

 

[niassu]

do u understand the critical mass too on nuclear enenrgy lesson
ops and for ur info. my edition is 2007 i think

 

[XPFMember]

wa allaikm el salam
me too have the radioactvity(2) imean the the questions ion the end of the page which is about
(If samples of strotium-90 and radium-226 both had the same activity today,which would have ythe lower activity in 10 years'time?????
thnx

Assalamoalaikum!!

no..that's fine..actually in ur first post u said about motors and generators...so that's y had a doubt...i'll look to ur question tomorrow inshaAllah! hope that u dont mind!!

 

[niassu]

wa allaikm el salam
me too have the radioactvity(2) imean the the questions ion the end of the page which is about
(If samples of strotium-90 and radium-226 both had the same activity today,which would have ythe lower activity in 10 years'time?????
thnx

Assalamoalaikum!!

no..that's fine..actually in ur first post u said about motors and generators...so that's y had a doubt...i'll look to ur question tomorrow inshaAllah! hope that u dont mind!!

donot mind ofcourse
ah and abt the first post my doubts is firstly in page 218 generators i dont understand hoew when the coil is vertical it cuts no magentic field ???

 

[XPFMember]

Assalamoalaikum!!!
Sooooo sorry ..i forgot to reply....InshaAllah will do it by tomorrow...so sorry!!

 

[XPFMember]

on page 259 i dont understand the first question.

Assalamoalaikum!!

Remember activity = (initial count rate) / 2^n
where n is the no. of half lives... and n = total time / time for one half-life

using this we can easily solve this question

If samples of strotium-90 and radium-226 both had the same activity today,which would have ythe lower activity in 10 years'time?????

let the initial count rate be x
first find n in order to find the activity of each...and then using the eqn. i gave above..find their activity

Sr-90

• n = 10 / 28 = 5 / 14
  so activity = x / (2^n)= 0.78x ...(substitute n and calculate..u'll get it..it's a fraction so if i substitute and show..it's gonna be messy )

Ra-226

• n= 10 / 1602 = 5 / 801
  so activity = x / (2^n) = 0.996x

hence Strontium - 90 will have the lower activity in 10 years time

Hope this helps..
sorry for the laaate reply
Jazak Allah Khair!

 

[XPFMember]

Assalamoalaikum!!

do u understand the critical mass too on nuclear enenrgy lesson

No i dont..it isn't there in the syllabus.. :geek: wasnt there atleast till last year..cant say if it's been added :roll:

 

[XPFMember]

Assalamoalaikum!!

in page 218 generators i dont understand hoew when the coil is vertical it cuts no magentic field ???

because when it becomes vertical..the direction of movement is parallel to the direction of magnetic field..hence no current is induced!!

Use Fleming's right hand rule..to understand this..u'll notice it urself
as u already know that the current and the direction of force shud be perpendicular..!! just try doing it..

if u still dont understand..let me know...i'll try to post some pics..to help u understand

 

[niassu]

Assalamoalaikum!!

do u understand the critical mass too on nuclear enenrgy lesson

No i dont..it isn't there in the syllabus.. :geek: wasnt there atleast till last year..cant say if it's been added :roll:

but i have found it in that book can u see page-260 (nuclear energy)

 

[niassu]

Assalamoalaikum!!

in page 218 generators i dont understand hoew when the coil is vertical it cuts no magentic field ???

because when it becomes vertical..the direction of movement is parallel to the direction of magnetic field..hence no current is induced!!

Use Fleming's right hand rule..to understand this..u'll notice it urself
as u already know that the current and the direction of force shud be perpendicular..!! just try doing it..

if u still dont understand..let me know...i'll try to post some pics..to help u understand

i would be pleased to see ur pics sorry for making u tired but "Jazak Allah Kairan" hope that god bless u for help
i m sorry but i have many other doubts too can i post next time or are u busy?????

 

[XPFMember]

but i have found it in that book can u see page-260 (nuclear energy)

Assalamoalaikum!!
but if u notice that there's a star/asterisk on it...which indicates that it's not necessarily in the syllabus!!

i would be pleased to see ur pics sorry for making u tired but "Jazak Allah Kairan" hope that god bless u for help
i m sorry but i have many other doubts too can i post next time or are u busy?????

well..not actually my pics will copy paste the link but not now..soon INSHAAllah

u post ur doubts...if not me others can help u too....when i get time and am in the mood to ...will reply

 

[niassu]

okay

 

[ChrisChin]

Personally I like Hodder but Pople is fine.

:: hi, plz if anyone can explain the electric motor, genrator and the lenz law , flemings right hand rule and eddy currents

The easy ones first:

Fleming's Right Hand Rule is a mnemonic used for generators. The individual fingers have the same meaning as in the left hand version, but point in a different direction relatively. Personally, I prefer to use the Right Hand Slap rule in teaching.

Eddy currents are small currents that flow in small circles, generated in metals by changing magnetic field. We use this knowledge recently for induction cookers.

OK -- Lenz's Law: The direction of induced current in a conductor will always be such that it will produce another magnetic field to oppose the relative change in the magnetic field causing the induced current.

Lenz's Law is a variation of the Principle of Conservation of Energy. In other words, you should remember that you cannot create energy from nothing -- so, where does the electrical energy that is generated come from? In fact, it comes from KE. Energy is converted from one form to another through work, so work must be done, or there will be no conversion. (Work=Force x Distance) Combine your understanding of Newton's 1st Law, Work, Energy -- you will also arrive at Lenz's Law.

 

[Noor]

Lenz's law is pretty okay for me..but ALL hand rules sound like latin to me so I should be grateful if you can explain in further details.