Physics: Post your doubts here!

[Zash Riyash]

http://www.cie.org.uk/images/157397-november-2012-question-paper-22.pdf

Question 5 part B please explain!
I know that p.d
AC = 4.8V
BC = 7.2V
AD = 8V
BD = 4V

Now it's asking pd between CD so wouldn't CD be either CB + BD
or CA + AD

But the answer is 3.2V which means they are subtracting... why??

They are subtracting it because they have said calculate the potential difference, which generally means that the difference in voltage. Hence, we must subtract. I hope you understood!

 

[yasoob_shah]

http://qualifications.pearson.com/c...2013/Exam materials/6PH07_01_que_20130509.pdf
question 2 4 and 5...help needed ASAP

 

[Zash Riyash]

Question 2 is D

 

[yasoob_shah]

Question 2 is D

dada why and how?

 

[Zash Riyash]

dada why and how?

Huh? We first convert mm to metres and then chose the median value which is .71 and addition of .1 would give .72 and subtraction of .1 from .7 would in turn give .69

 

[yasoob_shah]

Huh? We first convert mm to metres and then chose the median value which is .71 and addition of .1 would give .72 and subtraction of .1 from .7 would in turn give .69

ok tysm....got it...thnx one again

 

[nehaoscar]

They are subtracting it because they have said calculate the potential difference, which generally means that the difference in voltage. Hence, we must subtract. I hope you understood!

But then say they would've asked you the pd between A and B, then you would add the pd's right?
How do you know when to subtract and when to add?

And also say if they would've used 'voltage' instead of 'potential difference' then would you add?

 

[nehaoscar]

http://qualifications.pearson.com/content/dam/pdf/A Level/Physics/2013/Exam materials/6PH07_01_que_20130509.pdf
question 2 4 and 5...help needed ASAP

Question 4 is B
Frequency = 1/time period
Time period for one complete oscillation = 4 boxes = 4ms = (4 x 10^-3) seconds.
SO
Frequency = 1/(4 x 10^-3)
which = 250 Hz

 

[yasoob_shah]

Question 4 is B
Frequency = 1/time period
Time period for one complete oscillation = 4 boxes = 4ms = (4 x 10^-3) seconds.
SO
Frequency = 1/(4 x 10^-3)
which = 250 Hz

ohkayy thnxx alot

 

[Zash Riyash]

I just don't get it... Why would you ever add unless they ask the sum of the p.d, also if they had used the term voltage, then they would've certainly used the word, 'difference'.

 

[amal sharkawi]

Why the answer is B
Can anyone answer plz

 

[nehaoscar]

I just don't get it... Why would you ever add unless they ask the sum of the p.d, also if they had used the term voltage, then they would've certainly used the word, 'difference'.

So whenever they mention just pd, I subtract
and when they mention sum of pd, I add right?

So if in that question they said sum of pd accross CD then I would add the pd's right?

 

[Zash Riyash]

So whenever they mention just pd, I subtract
and when they mention sum of pd, I add right?

So if in that question they said sum of pd accross CD then I would add the pd's right?

Yup, but still google it, you might get a better idea.

 

[Lyfroker]

http://freeexampapers.com/A-Level/Physics/CIE/2002-Jun/9702_s02_qp_2.pdf

Q#1(b) & (d)

 

[Lyfroker]

http://freeexampapers.com/A-Level/Physics/CIE/2003-Jun/9702_s03_qp_2.pdf

Q#4(b)(i)

 

[Zash Riyash]

1.(b)= 3.6MJ

 

[Lyfroker]

http://freeexampapers.com/A-Level/Physics/CIE/2003-Nov/9702_w03_qp_2.pdf

Q#5(b)(i)

 

[Lyfroker]

1.(b)= 3.6MJ

How did you get it?

 

[Zash Riyash]

http://freeexampapers.com/A-Level/Physics/CIE/2003-Jun/9702_s03_qp_2.pdf

Q#4(b)(i)

For the first part I assume that it would be equal to the wavelength of light(from the spectrum)

 

[Zash Riyash]

How did you get it?

Power=joules/time
1 x 10^3= J/60 x 60
(1 x 10^3) x 3600= joules
=3.6MJ