Mark scheme for IGCSE Physics (0625/3) – Extended Theory November 2000
1
(a)
downward force through centre of mass
upward force along wire
downward force/weight = 5 N
upward force/tension = 5 N
2
3
4
1
1
1
1
4
(b)
weight/gravity/pull of earth
tension/pull of wire(on mass)
1
1
2
(c)(i)
(ii)
(iii)
continues straight line XY for any distance
line becomes curve of decreasing gradient to Z
1.5kg
12mm
1
1
1
1
4
(a)
change in property/length/volume per degree
(b)(i)
(ii)
nitrogen
gases expand more/most
1
1
1
1
2
(c)(i)
(ii)
copper
small increase in length per degree/high melting point etc
1
1
2
(d)
pointer movement not same for all degrees
effect different at different parts of the scale
1
1
2
(a)
use of p = hdg
= 6 x 1000 x 10
= 60 000 Pa
1
1
1
3
(b)
use of F = pA
(= 45 000 x 0.015) = 680 N
1
1
2
(c)
use of work done = Fs
(= 550 x 4) = 2200 J
1
1
2
(d)
at pulley (axles)
in person’s body
at block
work/energy used against friction force
or work/energy used in moving parts of the body eg. lifting arms
1
1
1
2
1
4 (max)
(a)
use of v = f x wavelength,
(= 0.8 x 1.6) = 1.3 m/s
1
1
2
(b(i)
1.6 m or same
1
5
6
7
(ii)
0.8 Hz or same
1
2
(c)
(part) circles
centred on middle of gap
not complete semicircles
1
1
1
3
(a)
use of specific heat capacity =
heat supplied/mass x temperature change
= 15 500/0.45 x 8.2
= 4 200 J/kgK
1
2
1
4
(b)(i)
(ii)
compress gas/ move piston in
use of p x V = c
substitution correct
v = 0.0034 m3
1
1
1
1
4
(a)
ray correct through F
ray correct through C or ray through other F
rays produced back to form image
1
1
1
3
(b)
sensible position, left of lens
1
1
(c)
image length 4.5 ± 0.2 cm
Approximately x 3 [e.c.f. from (a)]
1
1
2
(a)
use of R = V/I
6 ohm
1
1
2
(b)
two in parallel = 3 ohm
circuit total = 9 ohm
1
1
2
(c)
use of current = V/R
= 1.3 A
1
1
2
(d)
voltage across R less than 12 V / low / 8V or current through R
less than 2 A (1.3 (A)
or lower voltage means less bright or lower current means less bright
current through P and Q equal / voltage across P and Q equal
current through P/Q less than through R or p.d. across P/Q less than
across R
(e)
all three in parallel
1
1
1
3
1
1
8
(a)
any sine wave
amplitude approx 7V
2 correct full waves
1
1
1
3
(b)(i)
any mention of a magnetic field
conductor cutting field/lines
(so) induces emf (must be linked to cutting lines)
change in rate of cutting lines of force
coil rotates cuts one way then other
change in cutting direction reverses emf
1
1
1
1
1
1
4 (max)
electrons move from duster to rod
extra electrons on rod so -vely charged
hold rod close to plate
touch plate to earth it
remove rod leaves plate positively charged
1
1
1
1
1
4 (max)
(b)
alpha particles (strongly) ionise air
make air conduct electrons to the plate
(or in terms of conduction and neutralisation of charg(e)
1
1
2
(a)
A X
z
o e + A
-1
Z+1Y
correct mass no. and correct atomic number
1
1
2
(b)(i)
some beta absorbed by paper, some / most pass through
thicker paper less pass through / lower reading
no gamma would be absorbed by paper
gamma are less safe
1
1
1
1
4
smooth curve, either direction
curve towards bottom of page
1
1
2
(ii)
9
(a)(i)
(ii)
10
(ii)
(c)