How was 9702_w16_qp_42?

[Thought blocker]

Easiest of all right ? only electric field question was tricky . expected gt near 60 -65 . how about you guys

 

[iSean97]

Electric Fields how Point P? Paper 43 have the similar question.

 

[Thought blocker]

what was ur ratio, and speeds?

 

[ATEF RASHID 12]

i got ratio 1.5 and speed idr.

 

[Thought blocker]

i got ratio 1.5 and speed idr.

I got 1.5 too. speed max was sth 10^4 n at B was 10^3

 

[madhavmk]

i got max speed as 7000something and the next speed as 4000something
yeah 1.5 ratio
yeah the paper was quite easy.
many questions were repeat of previous papers especially balloon burst and ice melt

 

[Thought blocker]

i got max speed as 7000something and the next speed as 4000something
yeah 1.5 ratio
yeah the paper was quite easy.
many questions were repeat of previous papers especially balloon burst and ice melt

How u found he speed?
What was that answer ballon n ice??

 

[madhavmk]

the exact same question had come last years paper except it was a tyre bursting. See question 3 part B

 

[madhavmk]

The speed of particle question was quite tricky and a new one.
the E=V/d . we know maximum velocity is when no net force(equilibrium position in shm). so zer0 force acts when E=0.
E=gradient of graph(Potential gradient). so find when gradient =0(bottom point of graph).
find potential drop by subtracting the 2 potentials from surface of A and bottom. Energy gained = Vdrop * Charge(2 for alpha particle).
Equate energy gained to 0.5 mv^2 using mass of proton from data booklet *4 .
for 2nd velocity use potential drop from both surfaces instead of bottom of graph

 

[Thought blocker]

the exact same question had come last years paper except it was a tyre bursting. See question 3 part B
View attachment 61402

 

[Thought blocker]

The speed of particle question was quite tricky and a new one.
the E=V/d . we know maximum velocity is when no net force(equilibrium position in shm). so zer0 force acts when E=0.
E=gradient of graph(Potential gradient). so find when gradient =0(bottom point of graph).
find potential drop by subtracting the 2 potentials from surface of A and bottom. Energy gained = Vdrop * Charge(2 for alpha particle).
Equate energy gained to 0.5 mv^2 using mass of proton from data booklet *4 .
for 2nd velocity use potential drop from both surfaces instead of bottom of graph

I used o.5*m*v*2 = QV with same values of V. Is it correct?

 

[madhavmk]

I used o.5*m*v*2 = QV with same values of V. Is it correct?

i think we should us V drop rather than only the values of V.
But thats just my thought. none knows till marking scheme is published

 

[Sheikh Saif]

i got the same velocities for alpha particle like u guys..the velocities are too large
but here is the tricky part..
did anyone noticed the Voltage-distance graph..THE DISTANCE WAS IN CM!! and question askes veocity in M/S
and V=Q/4(pie)(epsilon0)(DISTNACE)
the voltage change will be greater and the vecity will be smaller..

 

[Thought blocker]

This 6 marks were tricky, else was easy!

 

[Sheikh Saif]

did anyone answered why rms current in the solinoid decreases for the iron core?

 

[Thought blocker]

did anyone answered why rms current in the solinoid decreases for the iron core?

Yes.

 

[Sheikh Saif]

Yes.

what was the answer?why rms currnet reduced? the iron core is not even a magnet..

 

[Thought blocker]

eddy currenyts

 

[madhavmk]

did anyone answered why rms current in the solinoid decreases for the iron core?

Inserting iron will increase the B value bcz it is ferromangetic. According F=BIL We can write as I=F/BL.
Thus the current inversely prop to B value. Hence if B increases the I value decreases