Physics: Post your doubts here!

[ashcull14]

Help needed with Nov09 (41) q8cii

BE per nucleon = BE * nucleon no.
according to law of conservation of energy total left hand side = total right hand side
as Q is the energy released not the energy holding the nucleons in a nucleus it will be subtracted from the equation
(2 × 1.12) + 3x = 28.28 –17.7
x= 2.78 Mev

 

[farhan141]

Does anyone have any notes/pics to explain how the LEDs are positioned in an amplifier circuit? I cant understand that.

 

[princess Anu]

http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-134.html
Q688
Part bi
Shouldn't the ans to part 1 be the ans to part 2 and vice versa?
Because if sampling freq is increased, more details can be recorded hence as the mark scheme says ' smaller changes can be recorded'
And if the no of bits are increased, higher freq can be recorded :s

 

[princess Anu]

BE per nucleon = BE * nucleon no.
according to law of conservation of energy total left hand side = total right hand side
as Q is the energy released not the energy holding the nucleons in a nucleus it will be subtracted from the equation
(2 × 1.12) + 3x = 28.28 –17.7
x= 2.78 Mev

Thank you so much

 

[princess Anu]

J10/41 Q9 bi why will the gain decrease?

 

[princess Anu]

Oct11/43
Q11c anyone??

 

[funky brat]

Oct11/43
Q11c anyone??

sharpness is how distinct the edges are which we can't tell unless we see an xray image but we can tell that there is a good contrast because there is a large difference between the absorption in the two media. Th regions that absorb more xrays appear darker than the other.

 

[ahmedish]

r u talking about ths
View attachment 60366

Yep.
Vout is positive, Green lights, which is in the correct orientation.

 

[ahmedish]

I agree :/

Its how it is in the book. I am fairly certain we are correct.

 

[princess Anu]

Its how it is in the book. I am fairly certain we are correct.

Yeah
My thought process is that when the Vout is +ve( switch is open),because I always flows from a higher potential to a lower potential,therefore I directIon will be from V out to earth, for the red diode to work it should be placed in a forward bias orientation

 

[Copy Cat]

 

[ahmedish]

June 12 P41
7c
why does the force vary at twice the frequency of current? it says it will vary by sin^2 x

 

[ahmedish]

View attachment 60392

Max p.d is 9 as
single capacitor has C=30
the parallel capacitors have C=60
as C=Q/V, C and V are inversely proportional so first Capacitor takes 2/3 of any p.d across AB.
The max pd across 1st capacitor is 6. so 2/3 of the pd across AB is 6
X*2/3=6
X=9

 

[ashcull14]

View attachment 60392

rules applied to capacitor are opposite to the ones in current electricity
voltage in parallel combination divides and current remains the same
and voltage in series is same and current divides
thus ..as max voltage is 6V..it divides equally between the both parallel capacitors..as each capacitor receives 3V the maximum pd across parallel combination is 3V..and across the one in series is 6V
total maximum pd = 6+3=9V between A and B

 

[ashcull14]

June 12 P41
7c
why does the force vary at twice the frequency of current? it says it will vary by sin^2 x

The magnitude of attractive magnetic force between the wires depends on the product of the currents and inversely on the distance between these two currents....product of currents = I^2 = sinosoidal and in phase ...thus f of the force varies by 2f of the current

 

[mistique_bee]

Rizwan Javed part b i? plz

 

[My Name]

View attachment 60406

Rizwan Javed part b i? plz

Year batana zara.

 

[mistique_bee]

Year batana zara.

oct/nov 2014 p21

 

[Rizwan Javed]

View attachment 60406

Rizwan Javed part b i? plz

First find the weight of the object:
W = mg = 5.09 * 9.81 = 49.9N

Then find it's base area : pi * r^2 = pi * (9.4/2 * 10^-2)^2 = 6.939 * 10^-3 m^2

So pressure will be,
P = F/A
Here force exerted is the weight, so
P = 49.9./6.939*10^-3
= 7195
~7200 Pa

 

[My Name]

First find the weight of the object:
W = mg = 5.09 * 9.81 = 49.9N

Then find it's base area : pi * r^2 = pi * (9.4/2 * 10^-2)^2 = 6.939 * 10^-3 m^2

So pressure will be,
P = F/A
Here force exerted is the weight, so
P = 49.9./6.939*10^-3
= 7195
~7200 Pa

You're fast!