232/2 – PHYSICS (THEORY) PAPER 2
KCSE MOCKS 2017
MARKING SCHEME
SECTION A:(25 MARKS)
1.
(2 marks)
2.
(3 marks)
3.Repulsion occurs only between like poles of a magnet. 1 Attraction can occur between a magnet
and a magnetic material and between unlike poles of two magnets.(1 mark)
4.- Polarization ½ – using a depolarizer ½ e.g. potassium dichromate.
- Local action ½ – pure zinc/amalgamation½(2 marks)
5.(a)Real image – formed on the screen.½
Virtual image – cannot be formed on the screen.½(1 mark)
(b)(i)- Side mirrors in cars.
- Security in supermarkets.(any one (1 mark)(1 mark)
(ii)- Headlamp reflectors.
- Torch reflectors.(any one (1 mark)(1 mark)
6.- Doping.
- Heating (increasing the temperature)(each one mark)(2 marks)
7.
(1 mark)
8.(a)- Has infinite resistance.
- Cannot be damage easily.(any one (1 mark)(1 mark)
(b)Period = 400ms
= 2.5HZ(2 marks)
9.A – Earth1
B – Live1
C – Neutral1(3 marks)
10.
(3 marks)
11.(a)- UV lamp (mercury vapour lamp).(any one (1 mark)(1 mark)
- Sun
(b)- Medical photography.
- Crystallography.
- Detecting metal flaws (clearing) industry.(any one (1 mark)(1 mark)
12.(a)P.d across 4 = 4 1.5 = 6V
Current through the 8 =
Current through the 10= 0.75 1.5(3 marks)
= 2.25A
V = 10 2.25A
= 22.5V
(b)I=
No of bulbs= (3 marks)
=
= 41 bulbs
(c)- Resistance.
- Time
- Currentany 2 (2mks)
13.(i)Maximum distance from rest position.1 or 1 Maximum distance from mean position. (1 mark)
(ii)(a)2S
(b) = 1 = 0.5 1(1 mark)
(iii)V =
340 = 0.5
= (3 marks)
(iv)- High density.
- Low temperature. each (1 mark)(2 marks)
14.(i)When the switch is closed the current in the coil A increases to a maximum value within a short time
1 Causing the magnetic flux linking with the coil B to increase the induced current at the same time
interval. Inducing an e.m.f in coil B causes a current flow hence a deflection in galvanometer 1
When switch is open the current in the coil A takes a very short time to fall from maximum to zero
since the magnetic flux in coil A linking coil B also falls from maximum to zero inducing an e.m.f
to the coil B, which is in the opposite direction 1(3 marks)
(b)- Flux leakage - reduced by efficient design of transformer i.e. Winding both coils on the same
transformer.
- Hystersis loss - Using core of soft magnetic material.
- Copper loss - Using thick copper wires.Any two
(c)(i)0 to 90 maximum to zero 1 induced e.m.f because the coils cuts the magnetic field pattern
perpendicularly producing maximum e.m.f , but the coil does not cut the magnetic field at
all when the angle is 90 producing no e.m.f , 90 to 180 zero to maximum 1 in the opposite
direction e.m.f because the coil rotates from position of no cutting to position of maximum
cutting of flux linkage in opposite direction. 1(2 marks)
(ii)
(2 marks)
15.(a)It is the minimum energy needed to completely remove an electron from the surface of a metal.
(b)(i)See graph paper.
(ii)(a)2.9 1014HZ
(b)VS =
Slope=
= 2.86 10-15VS
h = e slope
= 2.86 10-15 1.6 10-19
= 4.58 10-34JS
(c)Wo= hfo1
= 4.58 10-34 2.9 1014HZ
= 3.04 1019J
16.(a)- Positive charged proton ½ + Alpha particle ½
- Found inside nucleus protons ½ and neutrons. ½
- Occurs in equal numbers proton and electrons 1
(b)a = 232 1
b = 90 1
(c)(i)Radiations in the absence of radioactive radiation source. 1
(ii)- Cosmic rays
- The sun Any two
- Rocks
(iii)- Medicine
- Carbon dating Any one
- Detection of flaws
17.(a)Both have a virtual focus. 1
(b)Convex, converging lens 1
Magnified images are only formed by convex lens as only convex lens form real images.
(any 1mk)
(c)
1
(i)Long sightness. 1
(d)V + U = 72
M = 3
V = 3u 1
3u + u = 72
4u = 72
U = 18cm 1
1