Physics: Post your doubts here!

[Snowysangel]

What happens to time and amplitude if during oscillation half the mass gets detached at the highest point?

No effect on time...not sure aboutvanplitude

 

[unique111]

ohh k i understand but i am confused in the end why did u multiplied .39*.33 again with .39?

even I don't get why .39 is multiplied again. :/

and can somebody tell me where (-1.5) came from? In question 9bi?
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s10_qp_41.pdf

 

[Champ101]

even I don't get why .39 is multiplied again. :/

and can somebody tell me where (-1.5) came from? In question 9bi?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_41.pdf

You actually use the formula: Vout= gain* Vin
Vout = -3.5 * -1.5

-1.5 because it's connected to the negative terminal of the battery!

 

[unique111]

You actually use the formula: Vout= gain* Vin
Vout = -3.5 * -1.5

-1.5 because it's connected to the negative terminal of the battery!

lol. thanks yo!

 

[abubbaker khattak]

How many significant figures does our answer needs to be in a level physics paper 4?
i have been doing pastpapers and i loose a lot of marks by writing the answer in wromg number of significant figures!
can the examiner penalise me in every question or just once in the whole paper?

 

[Champ101]

How many significant figures does our answer needs to be in a level physics paper 4?
i have been doing pastpapers and i loose a lot of marks by writing the answer in wromg number of significant figures!
can the examiner penalise me in every question or just once in the whole paper?

3 significant figures or 1 decimal place. Its given in the instruction of the question paper only.

 

[Yousif Mukkhtar]

Guys, can someone explain Q 7 c) SHould high frequency mean higher rate of emission of electrons?
http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s13_qp_43.pdf

 

[A*(a*)]

ANYONE please solve this for me :'(

 

[Champ101]

Guys, can someone explain Q 7 c) SHould high frequency mean higher rate of emission of electrons?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_43.pdf

If the intensity is increased, more photo-electrons are emitted, but they have same max k.e.
Max k.e depends on frequency, i.e high frequency means high k.e.

 

[salvatore]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w13_qp_42.pdf
Please help me with qn no. 3(b)ii.. how do you calculate the total energy?
Thanks

 

[unique111]

***In an Op-amp, when Vout= 0 does that mean both input voltages from inverting and non-inverting are equal?
Help please!***

And question no. 10c ii) http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_41.pdf

Ques 10b) ho to draw the switch with the relay?
http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s10_qp_42.pdf

 

[unique111]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w13_qp_42.pdf
Please help me with qn no. 3(b)ii.. how do you calculate the total energy?
Thanks

From the graph, when amplitude (x) is .60 cm energy is 4mJ.

 

[unique111]

3 significant figures or 1 decimal place. Its given in the instruction of the question paper only.

I thought that depended on the values given in the question. If they are all given in 2 s.f shouldn't t your final answer be in 2 s.f as well?

 

[hellangel1]

In paper 5 and 3, how do we plot the points?
Do we enclose points in a circle or use a cross?

 

[unique111]

In paper 5 and 3, how do we plot the points?
Do we enclose points in a circle or use a cross?

Both are acceptable.

 

[salvatore]

From the graph, when amplitude (x) is .60 cm energy is 4mJ.

So why don't we consider the Ke while calculating the total energy?

 

[Yousif Mukkhtar]

If the intensity is increased, more photo-electrons are emitted, but they have same max k.e.
Max k.e depends on frequency, i.e high frequency means high k.e.

Yeah high frequency means high photon energy. But why does it mean that there will be less photons arriving per unit time?

 

[Champ101]

I thought that depended on the values given in the question. If they are all given in 2 s.f shouldn't t your final answer be in 2 s.f as well?

Yeah that too! but more significant number means less uncertainty...so 3 sf is much reliable. im talking about paper 4 here.
For paper 5, you're right!

 

[Champ101]

The no. of photons arriving per unit time depends on intensity. It doesn't depend on frequency. If less photons are arriving that means the intensity is less!

 

[Yousif Mukkhtar]

The no. of photons arriving per unit time depends on intensity. It doesn't depend on frequency. If less photons are arriving that means the intensity is less!

Why does the ms say that there are less photons arriving per unit time?