This document is a 7-page exam for Form Four Biology in Physics. It contains 3 sections - A, B, and C. Section A has 10 multiple choice questions testing concepts like density, momentum, and circuits. Section B has longer answer questions on topics like buoyancy, forces, pressure, and sound. Section C requires answering one of two extended response questions, one on semiconductors and transistors and one on thermionic emission and X-rays. The exam provides constants that may be used and instructs students to write in blue/black ink, show work, and include their name on each page.

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BIOLOGY FOR FORM FOUR
SUBJECT- PHYSICS
TIME 3HRS
INSTRUCTIONS
This paper consist three sections A,B and C
.Answer all questions in section A and B choose only one questions from section C
.All writings must be written in blue/ black ink or pen
except for diagram which must be drawn in pencil.
.Cellular phones and electronic calculators are not allowed in the examination room
Write your full name and stream on every page of the answer she
Where necessary the following constants may be used:
(i) Acceleration due to gravity (g)=10m/sec2
(ii) Density of water =1g/cm3
(iii) Linear expensively of iron =1.24 x 10=5
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(iv) Velocity of sound in air = 340m/s
(v) Pie = 3.14
SECTION “A” (20 Marks)
1.For each of the item(i)-(x) choose the most correct answer from the given alternatives and
write its beside the item number
(i) The density of most liquids decrease with the increase in temperature because
A. Increase while their masses remain constant
B. Increase more than their masses
C. Increase while their masses remain constant
D. Decrease while their masses remain constant
(ii) Which among the following pairs of physical quantities having the same meaning
A. Mass and weight
B. Velocity and speed
C. Impulse and momentum
D. Latent and specific heat capacity
(iii) The law of inertia
A. Deals with constant momentum
B. Is law of momentum
C. Is a property of a body to resist change of state
D. Is Newton`s second law of motion
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(iv) A body said to be in equilibrium if
A. Moves with uniform speed
B. The force acting on the body is clockwise moment
C. Acting toward the center of the earth
D. The upward force on the body counter balance some of downward forces
(v) If the body is 30 cm from the concave mirror of focal length 15 cm, the image
formed will be:
A. Upright
B. The same size as the object
C. Diminished
D. Virtual
(vi) Heat energy from the sun reaches the earth by
A. Radiation
B. Convection
C. Conduction
D. Light rays
(vii) A transistor is a device that
A. Amplify sound wave
B. Amplify current and voltage
C. Rectify current or voltage
D. Rectify sound wave
(viii) A current of 6MA flows in a radio with a resistance of 20 the P.d (v) across the
resistor is:
A. 1200 volts
B. 12 volts
C. 120volts
D. 0.12 volts
(ix) The cathode ray tube is used in the production of
A. X-rays
B. Cathode rays
C. Gamma rays
D. Infrared
(x) A 256 HZ turning fork produces sound at the same time with a 249HZ fork.The
beat frequency is:
A. 501HZ
B. 1.75HZ
C. 125HZ
D. 7.0HZ
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2 Match the items from the column “A” with column “B” and write its letter in space provided
below:
COLUMN A COLUMN B
(i) Lenz`s law
(ii) Faraday`s law
(iii) Mutual induction
(iv) Eddy current
(v) Rectifier
(vi) Slip ring
(vii) Efficiency of transformer
(viii) Electric motor
(ix) Step up transformer
(x) Silicone and germanium
A. A.C motor
B. D.C motor
C. Semiconductors materials
D. Used in wireless telegraph
E. Used in photograph
F. X 100%
G. X100%
H. Induced currents oppose the motion
I. Induced currents in the same direction
J. Work by the principle of Fleming’s left
hand rule
K. Works by the principle of Fleming’s
right hand rule
L. Number of turns in primary coil Is large
than the secondary coil
M. Number of turns in secondary coil is
large than the primary
N. E.m.f due to changing current in the
same conductor
O. E.m.f due to changing current In
another conductor
P. Direction of induced e.m.f
Q. The magnitude of the induced e.m.f
R. The device which makes current to
flows in one direction only
S. The devices which magnifies voltage
3.For each of the items (i) – (x) fill the blanks spaces by writing the correct answer in the answer
sheet
i. Is a device which produce almost unlimited supply number of charges by
induction_________
ii. A radioactive nucleus and decay to by emitting_________________
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iii. __________ is an instrument which can be used in submarine to view distant objects
which are out of direct vision
iv. ______________is the one which found at the edges of two plates moving toward each
other.
v. _______________is the space where an isolated north pole experience a force
vi. ________________formed when trivalent dopants added in the intrinsic semiconductor
vii. The heavy bodies seen in the sky holds in position by______________
viii. ____________is the maximum displacement of the wave
ix. Vacuum flask uses silvering to cut down heat transfer by
x. ___________occurs when two objects are moving relative to each other
SECTION B (60 marks)
4. (a) (i) State the law of floatation
(ii) Write down two conditions that make an object to float
(b) (i) Why the graduation scales in the hydrometer are wider on top while very close down
(ii) A block of wood float in water and displace 200cm3
of water. Calculate the weight
Of the block
5.(a) Define the following terms
i. force
ii Pressure
(b) i. Briefly explain ,when does the force becomes weight?
(ii) A car of mass 1200kg is brought to rest by a uniform force of 300N, in 80 sec.
What was the speed of the car?
(c) A rectangular log of wood of density 200kg/m3
has dimensions of 0.3m x 0.5m x 6.0m
(i) Calculate the maximum pressure it can exert on the ground(ii) Calculate the minimum
pressure it can exert on the ground. How can this be observed?
6. a) What is global warming?
b) Give four (4) effects of global warming
c) Explain four measures that can be taken to control global warming
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7. a) Explain the following terms
(i) Critical angle
(ii) Focal length
(iii)Optical center
b) Mention (2) conditions necessary for total internal reflection to occur.
c) A convex mirror produces a real image of an object which is half the size of the object
,if the distance between the object from the mirror is 90cm.calculate the distance of an image
from the mirror
8 a) Define the following terms
i. Radioactive materials
ii. Binding energy
iii. Half –life of radioactive
iv. Natural radioactve
b) A certain radioactive isotope decays by losing = particles followed
particles,followed by -particleas.Write the equation represent the nuclear charges
and show the mass ,atomic and proton number of the nuclide formed
9. a) Define the following terms
i. Echo
ii. Reverberation
iii. Overtone
b) Explain why a bat can fly in a dark without colliding with walls
c) A pipe closed at one end has length of 10cm. If the velocity of sound in the air of pipe
is 340m/s calculate the frequency of
(i) The fundamental
(ii) The first overtone
d) Give the reason why the frequency of the fundamental may alter during the day.
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SECTION C (20 Marks)
Answer one question from this section
10. a) (i) Name two semiconductor which are special importance in electronics
(ii) Explain how P-N junction diodes is formed and draw it`s symbol
b) (i) What do you understand by the term rectification?
(ii) Give out the differences between P-type and N-type semiconductors (5) points
c) Study the diagram below the answer the question below;
(i) Name the circuit of the transistor above
(ii) Why it`s called so?
(iii)Name the currents labeled by IB ,IE and Ic
11 a) What is thermionic emission?
b) What is the difference between hard and soft X- rays
c) Mention four (4) properties of X –ray
d) Draw a well labeled diagram of x – ray tube
………..The end………
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