PRESIDENT’S OFFICE

REGIONAL ADMINISTRATION AND LOCAL GOVERNMENT

MID TERM EXAMINATION AUG- 2023

SECONDARY EXAMINATION SERIES

PHYSICS FORM FOUR

031

TIME: 3 HOURS

Instructions

1. This paper consists of section A, B and C with a total of eleven (11) questions.
2. Answer all questions in section A and B and two (2) questions from section C.
3. Section A carries fifteen (15) marks, section B sixty (60) marks and section C carries twenty five (25) marks
4. Non programmable calculators and mathematical tables may be used.
5. Write your name or number on every page of your answer sheet.
6. Where necessary the following constants may be used.

• Acceleration due to gravity, g=10 m/s² or 10 N/kg
• Density of water =1.0 g/cm²
• Pie,=3.14
• Speed of sound is 340 m/s

SECTION A (15 Marks)

Answer all questions in this section

1.            For each of the items (i)-(x), choose the correct answer from among given alternatives, and write its letter beside the item number in the answer booklet provided.  (10 marks)

1.            A stone is thrown horizontally from the top of a building at a speed of 12 m/s. how long does it take to fall 45 meters vertically? (Assume negligible air resistance)

1.           1.0 sec              B. 5.0 sec      C. 3.0 sec        D. 8.0 sec      E. 2.14 sec

2.          In a race competition, one should kneel down when starting the race so that

1.           No one can fall down by reaction produced by the earth to them
2.            Each one can receive an acceleration which the earth provides
3.            One of the rules in sports is not violated by anyone
4.           Equal and opposite forces can act on a body to produce a resultant force.
5.             Each one could exert a force on the surface of the ground

3.         Heat would be lost in the thermos flask if the walls of the glass container were not coated with silver. Which process contributes to this kind of heat loss?

1.           Radiation
2.            Conduction
3.            Convection
4.           Absorption
5.             Transmission

4.         In a light experiment, observing an object through a certain material showed that less light was transmitted and the image was distorted. Which type of material was used

1.           A translucent material
2.            An opaque material
3.            A luminous material
4.           A transparent material
5.             A non-luminous material

5.          Why oil is used as lubricant

1.           It has low density
2.            It is highly viscous
3.            It is flammable
4.           It is less viscous
5.             It is costless

6.         When silicon element is doped with phosphorus atom, it produces:

1.           A P-type semiconductor
2.            Force
3.            An intrinsic semiconductor
4.           A bipolar semiconductor
5.             An n-type semiconductor

7.       A body is said to be in equilibrium if

1.           It moves with uniform speed
2.            The net force acting on it is zero
3.            The upward and downward forces are equal
4.           Its center of gravity is low positioned
5.             Its center of gravity is high

8.    What happens when a liquid changes into gaseous state?

1.           Some surface molecules absorb latent heat of vaporization and escape
2.            It gives its own latent heat that can be used to heat up the surrounding
3.            The potential and kinetic energies of the molecules increase
4.           The molecules attractive forces to one another increases and their average kinetic energy decreases
5.             There is no adhesive force between molecules.

9.        What is the main function of step up transformer?

1.           To change a.c to d.c current
2.            To decrease resistance in a circuit
3.            To increase a.c voltage
4.           To decrease a.c voltage
5.             To increase a.c current

10.          Which of the following arguments describes the mathematical language used in physics?

1.           Density is mass per volume
2.            Matter occupies space
3.            Volume is the amount of space occupied by the body
4.           Physics is the branch of science
5.             Action and reaction are equal and opposite

2.            Match the items in List A with response in List B by writing the letter of the correct response beside the item number in the answer booklet provided. (05 marks)

SECTION B (60 Marks)

Answer all questions in this section

3.            (a) Form one students from Mzumbe secondary school visited Kilimanjaro Mountain. When climbing the Mountain to high altitude, one of the students got the problem of nose bleeding.

1.            Comment on why student got such problem? ( 02 marks)
2.          Why astronauts wear space suits? (02 marks)

             (b)  The acceleration due to gravity on Jupiter is about 2.6 times that on the earth. A spacecraft has a weight of 24500 N on earth.

                     (i) What is the mass of the spacecraft?  (03 marks)

                     (ii) What would be its weight on Jupiter?  (03 marks)

4.            (a) What is the index if refraction for a certain medium, if the light in air enters the medium at an angle of 30° and refracted at 22°?  ( 04 marks)

(b) A vertical object 10 cm high is placed 20 cm away from a convex mirror of radius of curvature 30 cm. using a ray diagram, determine               (06 marks)

    (i) Image distance

    (ii) The height of the image formed

3.        The magnification of the image

5.            (a) (i) What do you understand the term Specific heat capacity and Specific latent heat of vaporization ( 02 marks)

     (ii) Explain the factors which affect the boiling point of water. (03 marks)

(b) A sample contains 800 g of Iodine-131. How much Iodine-131 in the sample will remain undecayed after 40 days, If the Half-life of Iodine-131 is 8 days?  (05 marks)

6.  (a)  Mr. Samwel put the coin on a card placed over the mouth of a bottle. When the card is flicked away with the figure the coin drops neatly into the bottle.

           (i) Which law demonstrated by Mr.Samwel? (01 mark)

          (ii)  State the law identified in (i) above (02 marks)

   (b)    A screw jack has a screw pitch of 5mm and the effort arm 16 cm  

          (i) State two forms of energy in which the energy supplied to the screw jack is finally converted     to (2 marks).

             (ii) Determine the percentage efficiency of this screw jack, if it needs an effort of 30N to lift a     load of 750N.  (04 marks)

7.  (a)  Describe how a lens camera operates the same as human eye. Give three points   (06 marks)

      (b)  Briefly explain how conduction of heat can be applied in your daily life (three reasons) (04 marks)

8.            Weather forecasting shows that there is the possibility of occurring earthquake in Mtakuja village. The villagers are not aware with such disaster. As physicist, make villagers aware with

1.          Meaning of earthquakes ( 02 marks)
2.         The four key indicators observed before an earthquake occurs (04 marks)
3.          Suggest four precautions to be taken by villagers during an earthquake in order to minimize injuries and deaths. (04 marks)

SECTION C (25 MARKS)

Answer two (02) questions in this section.

9.            (a)  George Ohm observed that as the current flows through the circuit, it encounters some opposition. This opposition determines the amount of current flowing in electric device depending to the particular material.

(i) State the law that Mr. George formulate. (02 marks)

     (ii) Briefly explain factors affecting resistance of a conductor observed by Mr. George Ohm to sum up his observation. (04 marks)

   (b) (i) Distinguish between the concept of conductors, semiconductor and insulators in term of energy bands (04.5 marks)

        (ii) Give out one structural difference between A.C and D.C generators. (02 marks)

10.        (a) Briefly explain how length of the string affects frequency of vibrating string. (02 marks)

(b) A string has length of 75 cm and a mass of 8.2 g. the tension in the string is 18 N. What are the frequencies of the 1^st and 3^rd harmonics? (06 marks)

(c) A transformer is used to step down 240 V mains supply to 12 V for laboratory use. If the primary coil has 600 turns, determine the number of turns in the secondary coil. (04.5 marks)

11. (a) Why some semiconductors called P type and other called N type? (3 marks)

          (b)  Describe, how you will connect the semiconductor diode as forward bias.  (4 marks).

        (b) The jaws of a vernier caliper touch the inner wall of calorimeter without pressure. The position of zero of vernier scale on the main scale reads 3.4 cm. the 6^th of vernier scale division coincides with the main scale division. Vernier constant of calipers is 0.01 cm. Find actual internal diameter of calorimeter, when it is observed that the vernier scale has a zero error of -0.03 cm. (5.5 marks)

THE PRESIDENT'S OFFICE

MINISTRY OF REGIONAL GOVERNMENT AND LOCAL GOVERNMENT

MID TERM EXAMINATION

PHYSICS FORM-4

2021- AUG/SEPT

TIME: 2:30 HRS

Instructions

1.   This paper consists of sections A, B and C with a total of eleven (11)  questions.
2.    Answer all questions in sections A and B and two (2) questions  from section C.
3.    Cellular phones and any unauthorised materials are not allowed in  the examination room.
4.    Non-programmable calculators may be used.
5.    Write your Examination Number on every page of your answer  booklet(s).
6.   Where necessary the following constants may be used:

1.  Acceleration due to gravity, g = 10 m/s ²
2. Density of water = I .0 g/cm³
3. Pie= 3.14.
4.  Coefficient of linear expansivity of the brick 1.2 x 10 ^-5K ^-1
5.  Speed of light in air = 3 x 10⁸ m/s. 
6. Speed of sound in air = 340 m/s.

SECTION A (15 Marks)

Answer all questions in this section.

1. For each of the items (i) - (x), choose the correct answer from among the given alternatives and write its letter beside the item number in the answer booklet provided.

(i)Why is Mercury preferred in clinical thermometers as a thermometric of a liquid to water and alcohol?

1. It is denser than other liquids.
2. It is opaque and does not need colouring.
3. It is more sensitive to temperature.
4. It is active and does not wet the glass. 
5. It is a poor conductor of heat.

(ii)Which process is involved in producing reverberation?

1. Refraction
2. Multiple reflection 
3. Interference 
4. Diffraction
5. Reflection

(iii) Which pairs of instruments would you use to correctly measure the diameter of a small ball bearing?

1.        Measuring tape and vernier caliper
2.        Slide rule and micrometer screw gauge
3.        Vernier caliper and slide rule
4.        Micrometer screw gauge and vernier caliper
5.        Metre rule and micrometer screw gauge

(iv) Which phenomena is a result of the earth being exactly along the same line between the centre of the sun and the moon?

1.       Lunar eclipse
2.       Penumbra
3.       Solar eclipse
4.       Umbra
5.        Reflection

1.  It is because the sun warms the car by induction.
2.  It is because the sun gives energy to the wheel by convection.
3.  It is because the sun radiates thermal energy to the wheel.
4.  It is because the sun radiates heat to the glass windows.
5. It is because the sun conducts thermal •energy to the wheel.

(vi)Which one is a characteristic of a plane mirror?

1. It forms image which is real and opaque.
2. It forms an image which is larger than the object.
3. It forms an image which is real and laterally inverted
4. It forms an image which has the same size as the object.
5. It forms an image which is smaller in size than the object.

(vii)When silicon element is doped with phosphorus atoms, it produces

1.   a p-type semiconductor
2. force
3. an intrinsic semiconductor
4. a bipolar semiconductor
5. an n-type semiconductor

(viii) What will be the resistivity of a wire 2 metres long with a cross-sectional area of 0.50 mm² and a resistance of 2.20? 

1.  5.5 x 10^-7 ?m 
2.  6.5 xlO^-7?m 
3. 2.3 x 10^-7 ?m 
4.  1.1 x 10-⁶?m
5.  5.5 x 10^-6?m.

1.  magnifying lens
2.  plan mirror
3. telescope
4.  optical fibre
5.  pin-hole camera 

1.   Between Mercury and Venus
2.  Between Earth and Mars
3. Between Mars and Jupiter
4. Between Saturn and Uranus 
5. Between Neptune and Pluto

2. Match the following items

SECTION B (60 Marks)

Answer all questions in this section.

3. What do you understand by the following terms?

(i) Work 

(ii) Energy 

(iii) Power 

(b) Calculate the power of a pump which can lift 200kg of water through a vertical height of 6m in 10 seconds, given g =10m/s².

(c) Explain the meaning of the following terms:

(i)Kilowatt . 

(ii)Kilojoules . 

4.(a) (i) What is acceleration?

(ii) A car with a velocity of 60km/h is uniformly retarded and brought to rest after 10 seconds. Calculate its acceleration.

(b) (i) Distinguish between distance and displacement.

(ii) Provide one example of the law of inertia of a body.

(c)What is the mass of a body which when acted on by a force of 3N accelerates at 7m/s².

5.Define the term light.

(b) By aid of a diagram state the laws of reflection.

(c)How many images can be formed if two mirrors are set:

(i)At angle of 60 ⁰?

(ii)Parallel to each other? 

6.(a) What are the uses of the following devices?

(i)Manometer

(ii)Heres apparatus (inverted U-tube) 

(iii) U-tube ....

(iv) Barometer 

(b) Explain why a big elephant manages to walk comfortably in maddy soil without sinking while a human being may sink easily.

(c) Draw a well labelled diagram which demonstrates that liquid pressure depends on depth.

7. (a) (i)What is meant by radioactive decay?

 (ii) Give two effects of beta (β) particle on the nucleus of an atom.

(b) (i)Define the term isotope of an element. 

(c) (i)How would you test whether a car battery needs recharging? (Give three points).

(ii) Two resistors each of 5 Ω Are connected in parallel across the same battery of e.m.f. 5 V and negligible internal resistance. If the battery is fully charged and then discharged within 20 hours, calculate the storage capacity of the battery.

SECTION C (25 Marks)

Answer two (2) questions from this section

9. (a) What is meant by the following terms?

(i)Volcanoes

(ii) Non-renewable sources of energy.

(b)(i) Mention two merits and two demerits of volcanoes.

(ii) Briefly explain two hazards associated with earchquakes.

(c) (i) List down two disadvantages of non-sustainable energy sources.

(ii) State two applications of energy generated from water.

11. (a) (i)Use the kinetic theory to explain why solids expand when heated.

 (ii)Mention two experiments which can be done in the laboratory to verify thermal expansion of solids. 

(b) Explain how each of the following works:

(i) a bimetallic thermostat.

(ii)a bimetallic thermometer.

(c) (i) What is an induction coil?

(ii) Describe the structure of an induction coil and briefly explain its mode of action.

10. (a) (i) State the laws of electromagnetic induction.

(ii) Mention two advantages of a.c. generators over d.c. generators.

(b)(i) Briefly explain why the core of a transformer is made of thin layers of metal insulated from one another.

(ii) Describe the structure of a step-up transformer and state how it works.

(c)A transformer with 4800 turns in the primary coil is designed to work form 240 V a.c. mains to give a supply of 8 V in order to ring a bell.

1. What would happen if the transformer were connected to a 240 d.c. mains?
2. Briefly explain why the primary current increases when a bell is being rung?

11. (a) Explain briefly the following:

(i) Thermionic emission (1 mark)

(ii) The production of a stream of electrons in a cathode ray oscilloscope (c.r.o.). (1 mark)

(iii) The principle of the transistor. (1 mark)

(b) What method in devices using the thermionic emission principle ensures that the electrons produced:

(i) do not accumulate at the source? (1 mark)

(ii) reach their target undeviate? (1 mark)

(iii) travel without meeting other forms of particles on their way to the target? (1 mark)

(b)(i) To ensure that the electrons produced do not accumulate at the source, the devices have anodes for accelerating the electrons from the source.

(ii) For the electrons to reach their target undeviated, the devices have a focusing anode.

(iii) The devices using the thermionic emission principle are evacuated so that electrons travel without colliding with other particles on their way to the target.