Mark scheme for IGCSE Physics (0625/3) – Extended Theory May/June 2001
1
2
(a)(i)
(ii)
uniform acceleration
uniform speed / terminal velocity
1
1
2
(b)
20s
1
1
(c)(i)
(ii)
force of gravity / weight downwards
force of gravity / weight downwards and resistance / upthrust upwards
2
2
3 (max)
(d)(i)
(ii)
yes
no
(e)
distance = area under graph / 0.5 x 5 x 48
= 120m
1
1
2
(a)
momentum = mass x velocity / momentum = 800 x 20
= 16 000
kg m/s
1
1
1
2 (max)
(b)(i)
momentum change = 16000 - 4000
force = 12 000/4 = 3000 N
deceleration = speed change / time
= 15/4 = 3.8m/s 2
1
2
1
2
6
(a)
diagram showing balance and measuring cylinder
suitable labels
1
1
2
(b)
balance reading for mass
two volume readings
1
1
2
(c)
volume of stone from start and finish readings
density = mass / volume
1
1
2
(a)
suitable random path
1
1
(b)
air molecules hit particles
any two of:
molecules moving very fast / particles more massive / many hits
per particle / hits uneven
1
(c)
any two of: bigger movements / faster movements / air molecules faster
2
2
(a)
heat input = power x time / 50 x 600
temperature change for liquid = 45°C
heat gained by liquid = mass x s x temperature change / 200 x s x 45
s = 30 000 / 9 000
1
1
1
1
(ii)
3
4
5
1
1
1
2
2 (max)
= 3.3
J/(g K)
(b)(i)
(ii)
6
(a)(i)
8
2
1
3
1
1
1
1
4
(b)
i = 32°, and r = 20°
R.I. = sin i / sin r
= sin 32° / sin 20°
= 1.55
1
1
1
1
4
(a)
direction sound (wave) is travelling
1
1
(b)(i)
(ii)
(iii)
pressure varies along sound wave / some particles closer than others
very few particles at P / P is a rarefaction
many particles at Q / Q is a compression
1
1
1
2 (max)
(c)
vibrates / oscillates / moves backwards and forwards
along the direction of the wave
1
1
2
(d)
40 mm
1
1
(a)(i)
current = power / voltage or = 0.6 / 1.5
= 0.4 A
resistance = voltage / current or 1.5 / 0.4 (e.c.f.)
= 3.8 ohm
charge = current x time or = 0.4 x 20 (e.c.f.)
=8C
1
1
1
1
1
1
5 (max)
two lengths in parallel
correctly shown on Fig. 8.2
two lengths in series
correctly shown on Fig. 8.3
1
1
1
1
3 (max)
(c)
energy = l x l x R x t or V x l x t
= 0.6 x 0.6 x 5 x 20
= 36 J
1
1
1
3
(a)(i)
any method of induction
any mention of magnetic field
changing / alternating
core transmits (changing) magnetic field from primary to secondary
1
1
1
1
(ii)
(iii)
(b)(i)
(ii)
9
any two of: heat lost to atmosphere / temperature rise less / bigger by
reference to equation
any one of: lagging / lid etc
any attempt shown to mark or measure critical angle
critical angle = 40° (not 42°)
incident angle at Q greater
>40o (> than candidate’s value i.e. e.c.f.)
(ii)
7
1
1
5 (max)
2
(ii)
no change in magnetic field
energy not transferred from primary to secondary
1
1
5 (max)
(b)(i)
voltage ratio = turns ratio
2000 turns on primary
primary voltage x primary current = sec voltage x sec current
0.2 A
1
1
1
1
4
each correct entry scores one mark
mass of nucleus (much) greater than alpha particle
after collision effect on alpha particle greater
positive charge
repulsion from the positive nucleus
most alpha particles pass straight through
most of atom space or nucleus much smaller than atom
5
1
1
1
1
1
1
5 (max)
(ii)
10
(a)
(b)(i)
(ii)
(iii)
3