May15 Physics HL Paper 1 & 2

[Kv19971]

 

Btw. There was a question on green light being emitted from two point sources, which had just NOT been resolved. So the options asked how to resolve it and there were two contrasting ones: red light and using a circular aperture. Both would increase the angle theta so what'd you write? 

 

(I should be revising for Chem and CS right now )

The answer to that question was using the red light. Red light has a minimum wavelength of 620nm. Blue light has a minimum wavelength of 550nm. 

Since 1.22*550 < 620, the answer should have been red light since it increases the value of theta more than using a circular aperture would.

[Megamind]

 

 

Btw. There was a question on green light being emitted from two point sources, which had just NOT been resolved. So the options asked how to resolve it and there were two contrasting ones: red light and using a circular aperture. Both would increase the angle theta so what'd you write? 

 

(I should be revising for Chem and CS right now )

The answer to that question was using the red light. Red light has a minimum wavelength of 620nm. Blue light has a minimum wavelength of 550nm. 

Since 1.22*550 < 620, the answer should have been red light since it increases the value of theta more than using a circular aperture would.

 

 

I know right I ticked red light too, but some people are saying it should be violet light. But aren't we supposed to increase the value of theta, thereby using red light? 

[Hassan76]

Theta is the required angle to be resolved, like a price, so you want to reduce the price not to increase it right ? So you want theta to be smaller so that there is less diffraction

[Yuki Kuran]

Paper one was a disaster, but paper 2 was easy;)

In paper 1, I think there was a question, where two answers were correct just like the aperture/green light one.

It said that a particle with mass m, charge q had radius r in a unuform magnetic field. If another particle entered and had the same radius r, what could be its mass, charge and velocity.

I have solved it

mv^2/r=qvB

mv/r=qB

mv/q=Br

I think that it had options 2m, 2q, v and 2m, q, v/2

Edited May 15, 2015 by Yuki Kuran

[mechnight]

Paper one was a disaster, but paper 2 was easy;)

In paper 1, I think there was a question, were two answers were coorect just like the aperture/green light one.

It said that a particle with mass m, charge q had radius r in a unuform magnetic field. If another particle entered and had the same radius r, what could be its mass, charge and velocity.

I have solved it

mv^2/r=qvB

mv/r=qB

mv/q=Br

I think that it had options 2m, 2q, v and 2m, q, v/2

 

Yep, I think I had it like you as well.

[Hassan76]

Paper one was a disaster, but paper 2 was easy;)

In paper 1, I think there was a question, were two answers where correct just like the aperture/green light one.

It said that a particle with mass m, charge q had radius r in a unuform magnetic field. If another particle entered and had the same radius r, what could be its mass, charge and velocity.

I have solved it

mv^2/r=qvB

mv/r=qB

mv/q=Br

I think that it had options 2m, 2q, v and 2m, q, v/2

No,there is one answer,for this reason mcq is tricky, however after recieving feedback they may accept 2 answers or discount a question for example if the question was asked ambigiously Edited May 15, 2015 by Hassan76

[Yuki Kuran]

Paper one was a disaster, but paper 2 was easy;)

In paper 1, I think there was a question, were two answers where correct just like the aperture/green light one.

It said that a particle with mass m, charge q had radius r in a unuform magnetic field. If another particle entered and had the same radius r, what could be its mass, charge and velocity.

I have solved it

mv^2/r=qvB

mv/r=qB

mv/q=Br

I think that it had options 2m, 2q, v and 2m, q, v/2

No,there is one answer,for this reason mcq is tricky, however after recieving feedback they may accept 2 answers or discount a question for example if the question was asked ambigiously

Do you think that someone has reported it?

[Hassan76]

Paper one was a disaster, but paper 2 was easy;)

In paper 1, I think there was a question, were two answers where correct just like the aperture/green light one.

It said that a particle with mass m, charge q had radius r in a unuform magnetic field. If another particle entered and had the same radius r, what could be its mass, charge and velocity.

I have solved it

mv^2/r=qvB

mv/r=qB

mv/q=Br

I think that it had options 2m, 2q, v and 2m, q, v/2

No,there is one answer,for this reason mcq is tricky, however after recieving feedback they may accept 2 answers or discount a question for example if the question was asked ambigiously

Do you think that someone has reported it?

No need to report it, btw I chose the false response and didn't notice there 2 were valid, but the idea is that the velocity selector is explicitly explained in the books. So v is not changed, for this reason what is displayed is m/q ratio

[sam1996]

What did you get for the impossible electron in a box momentum? I guessed D, the one with 4 in the denominator

[Yuki Kuran]

What did you get for the impossible electron in a box momentum? I guessed D, the one with 4 in the denominator

I also chose the one with 4. Don't know why.

Edited May 16, 2015 by Yuki Kuran

[Hassan76]

I do not remember the possible choices but here is how you do it, p= lambda/ h

Lambda = 2L/n, n is an integer and cannot be o.5 for example so , h/4l is not possible