Physics: Post your doubts here!

[Thought blocker]

I don't understand mark scheme for drawing the circuit. Can anyone help me with drawing that and i don't understand why the terminals of external circuit is attached to the earthing.

A2 level ?

 

[sudeep1097]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_42.pdf

Q6b (ii)

Why is there a potential difference between face BCGF and face ADHE ?? i don't get it


Q11 b (ii)

6b(ii)
By fleming's left hand rule electrons experience force in direction of BCFG. Note: The second finger should point in opposite direction of velocity of electrons. This has set up a potential difference (known as hall voltage) across the conductor since BCFG is negative so ADHE will be positive with respect to BCFG.

11b(ii)
sampling frequency = 44.1 Khz
Since each sample consists of 16- bit word, bit rate(bits per second) = 44.1 x 1000 x 16
Now,
time for recording = (5 x 60) + 40 s = 340 s
number of bits generated in recording time = 340 x bit rate

 

[sudeep1097]

A2 level ?

Yup it's about relays and diodes.

 

[Thought blocker]

Yup it's about relays and diodes.

So much to study in A2 level... I am in As

 

[sudeep1097]

So much to study in A2 level... I am in As

Haha don't worry! A2 is difficult but if you set out a routine and study accordingly it will be a breeze! I have to give two full a levels (chemistry and physics) and two a2 levels ( bio and maths) this may june but just started preparing today! quite worried! How about visting my new chat thread to share your anxieties

 

[Suchal Riaz]

.

14- the direction of force would be opposite to the direction of field. one way to think about it is that as F=eV/L and e is negative the force will be in opposite direction. or you can think that the electric field shows the path taken by a unit positive charge so electron, having opposite charge, would move in opposite direction.
the direction of field at that exact point would be tangent to that point. so clearly A is the answer.

16- alpha particle has a positive charge and so does a nucleus. so the alpha particle and nucleus repel each other. the alpha particle closer to the nucleus would bend more and alpha particle away from nucleus would bend less but both will bend away from nucleus. so answer is B

18-

 

[Thought blocker]

14- the direction of force would be opposite to the direction of field. one way to think about it is that as F=eV/L and e is negative the force will be in opposite direction. or you can think that the electric field shows the path taken by a unit positive charge so electron, having opposite charge, would move in opposite direction.
the direction of field at that exact point would be tangent to that point. so clearly A is the answer.

16- alpha particle has a positive charge and so does a nucleus. so the alpha particle and nucleus repel each other. the alpha particle closer to the nucleus would bend more and alpha particle away from nucleus would bend less but both will bend away from nucleus. so answer is B

18- View attachment 38584

18 part was a bit confusion, but it is cleared. Ty

 

[saqib.tariq]

Physics as level notes neeeded PLZZZZZZZZZZ anyone ????

 

[Thought blocker]

Best notes

Physics as level notes neeeded PLZZZZZZZZZZ anyone ????

 

[saqib.tariq]

these notes are really confusing but thanks i wanted for AS only

Best notes

 

[Suchal Riaz]

.

20- take readings of current at zero volt and take the ratio
22- 0-6V because max volts of 20 volt resistor is 20*12v/(20+20)
24-
the resultant is zero because the force on + and - is same and opposite so it will cancel out..
the forces on + and - would be equal and opposite so a torque of a couple will cause it rotate anticlockwise .

 

[Anzuman turin]

thanks alot bro . it helped alot btw bro 24 ans is c according to ms . please explain the rest questions too bro

 

[Suchal Riaz]

Anzuman turin
26- the circumference = distance travelled by one point charge in one round. frequency means rotation per second. there are four of the point charges. so total charge pass in one second will be 4 X (2πr) X Q X F=8πrQf

 

[Suchal Riaz]

Anzuman turin
28- if it is in equilibrium the moment must be zero. as we don't know the friction and contact forces at X take moments about it so the moment of reaction forces are zero.
10 is half the distance from X than Y so it's moment will be 10N X 0.5XY
the perpendicular component of force F is F sin30 and it's distance is XY
they must be same. 5XY=Fsin30 XY
5=0.5F
F=10
if you realise that the angle is 30 degree and it's sine in 0.5 this could be done in mind.

 

[Anzuman turin]

Anzuman turin
26- the circumference = distance travelled by one point charge in one round. frequency means rotation per second. there are four of the point charges. so total charge pass in one second will be 4 X (2πr) X Q X F=8πrQf

ans is a A bro

 

[Suchal Riaz]

forgive me i didn't sleep last night and i don't know what i am saying. i confused it with the question in which the distance was found for work done.
I don't know why i multiplied distance.
charge per point = Q, charge pass per round=4, round per second=f
A=charge/time=charge.frequency while charge being 4Q
giving us 4Qf as final answer.

 

[Anzuman turin]

forgive me i didn't sleep last night and i don't know what i am saying. i confused it with the question in which the distance was found for work done.
I don't know why i multiplied distance.
charge per point = Q, charge pass per round=4, round per second=f
A=charge/time=charge.frequency while charge being 4Q
giving us 4Qf as final answer.

got it . thanks for the help bro . please help with other questions when you are ok

 

[daredevil]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_42.pdf

Q11 c) shouldn't the fraction here be Pin/Pout when calculating attenuation?? [considering attenuation to be positive] ??

Q5 b (i) and c

 

[ShreeyaBeatz]

People,
Tell me how to find the minimum pd here:

A cell of e.m.f. 2.0 V and negligible internal resistance is connected to a variable resistor
R and a metal wire,
The wire is 900 mm long and has an area of cross-section of 1.3 × 10–7 m2. The
resistance of the wire is 3.4 Ω.The resistance of R may be varied between 0 and 1500 Ω. What is the minimum pd?
according to markscheme- ans=4.5 x 10^-3
its of 9702/21/O/N/11 please help!

 

[sitooon]

Can someone draw the diagram ?