UNEB UCE PHYSICS PAPER 1 Nov./Dec. 1993

UNEB 1993

1.  A thermopile is an instrument which converts

A.  heat energy to electrical energy

B.  electrical energy to light energy

C.  light energy to electrical energy

D.  chemical energy to heat energy

2.  A uniform tube with a narrowed middle part has three identical manometers attached to it as in the figure bellows

If a steady flow of a liquid is maintained in the direction indicated by the arrows, the height of the liquid will be

A.  greatest in X  B.  greatest in Y

C.  greatest in Z  D.  equal in X, Y and Z

3.  A house has four 75 W lamps and five 100 W lamps. What will be the cost of running the lamps for 10 hours if the cost per kWh is sh.50

A.  sh.250,000  B.   sh. 40,000

C.   sh. 50,000  D. sh. 78,750

4.  When a yellow dress with blue dots is placed in a room lit with pure red light, the dress appears

A.   red with black dots B.  yellow with blue dots

C.   green with red dots D.   black with yellow dots

5.  The figure below shows a Vernier callipers with an object Y between its jaws

The diameter of Y is

A.  1.05cm B.   1.06cm

C.  1.56cm D.  1.60cm

6.  If ^a_bX and ^c_dY are isotopes, then

A.  a=c B.  a=d C. b=c D.  b=d

7.  An image 5cm high is formed by a converging lens. If the magnification is 0.4, find the height of the object

A.  2.0cm B.   4.6cm C.  5.4cm D.  12.5cm

8.  It is more difficult to compress a liquid than a gas because

A.  the speed of liquid molecules is lower than that of gas molecules

B.  liquid particles attract one another when compressed while gas particles repel each other

C.  the distances between liquid particles are less than those between gas particles

D.  liquid molecules repel one another when compressed while gas molecules repel one another

9.  It is recommended that buildings should have earthed colours in order to

A.   reduce heat intensity on hot days  

B.  remove excess electrons from the building

C.  stabilise the current electricity to the building

D.  provide more charges to electrical appliances in the building

10.  A mass of 0.5kg causes a spiral spring to extend by 4cm. The force that would cause an extension of 6cm would be

A.  2.0N B.  3.3N  4.8N D.  7.5N

11.  When a person steps forward from rest, one foot pushes backwards on the ground. The ground will as a result push that foot

A.  backwards with an equal force B.  forwards with an equal force

C.  backwards with a smaller force D.  forwards with a smaller force

12.  Which one of the following graphs shows how the density of water varies with temperature between 0⁰C and 100⁰C

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13.  An electric heater is used to heat 0.2kg 0f water for 200s. find the p.d across the heater of the current through it is 0.5A and the temperature of the water rises by 25⁰C

A.  145V B.  175V C.   210V D.  240V

14.  If the system in fig.3 is in equilibrium, find the value of X

A.  30N B.   50N C.  60N D.  90N

15.  A current of 2A flows in a circuit in which two resistors each of 3Ω, are connected as shown in fig.4 calculate p.d across XY

A.  1.5V B.  3.0V C.  6.0V D.  12.0V

16.  The graph in fig.5 is that of temperature against time for a substance which is heated at a constant rate

Which part of the graph corresponds to the situation when the molecules of the substance have the highest average kinetic energy

A.  OV B.   VW C.  WX D.  YZ

17.  Rectification of alternating current means

A.  stepping up alternating current by a transformer

B.  converting alternating current into direct current

C.  stepping down alternating current by a transformer

D.  generating alternating current from a dynamo

18.  A car of mass 1.5×10³kg climbs a hill in 900s. If the top of the hill is 50m above the starting point find the average power output of the engine.

A.  1.38x10W B.  8.33×10²W

C.  5.00×10³W D.  50×10⁵W

19.   Which one of the following sets of substances can be used when electroplating an iron ring with silver?

  Cathode   Anode Electrolyte

A. Silver ring copper(II) sulphate

B. Ring silver copper(II) sulphate

C. Ring silver silver nitrate

D. Silver ring silver nitrate

20.

When the handle, H, of the force pump shown in figure above is moved upwards, the valves at

A.   F and G will both close  B.  F and G will both open

C.  F will close, and G will open  D.  F will open and G will close

21.   Find the force that acts on a body of mass 0.05kg accelerating at 20ms^-2

A.  1.0N B.  10N C.  100N D.  400N

22.  The process by which heavy nuclei split to form lighter nuclei is called

A.  fusion B.  fission C.  Ionisation  D.  Radioactivity

23.  A vibrator produces waves which travel a distance of 35cm in 2s. If the distance between successive wave crests is 5cm, what is the frequency of the vibrator

A.  3.5Hz B.  7.0Hz C.  14.0Hz D.  87Hz

24.  Mercury forms spherical drops when spilt on a wooden bench because it

A.  is very viscous B.  has a high density

C.  has a high cohesive force D.  has a low surface tension

25.  A car travelling at 20ms^-1 is brought to rest in 10s. Find the distance it travels

A.  100m B.  200m C.   300m D.   400m

26.   The diagram below shows a structure of wooden beams P, Q, R, S and T supporting a heavy rod L

Which of the beams can be replaced by ropes if the same shape is to be maintained

A.  P, R, S and T   B.  P ,Q,S and T C.  Q,R,S and T D.   P,Q,R and S

27.  Which one of the following is the correct order in which some energy changes occur in the electron gun of the cathode ray tube?

A.  light → heat →  K.E

B.  electric  →  light  →  heat

C.  Electric  →  heat  →  K.E

D.  sound →  electric→  heat

28.  The half life of a radioactive material is 20 days. Find the initial mass of the material if 2g of it remains after 80 days

A.  4g B.  8g C.  16g D.  32g

29.  A body dropped from the top of a high building falls with uniform velocity when

A.   the pull of gravity stops acting on it

B.   the resultant force is towards the ground

C.  the pull of gravity is balanced by air resistance

D.  the resultant force is equal to the pull of gravity

30.  A transformer can’t function normally with a d.c because a d.c

A.   has an extremely high heating effect

B.   reduces the efficiency of the transformer

C.   Cannot produce a changing magnetic field

D.   Cannot provide high voltages required for power transmission

3 1.  When the nucleus of a radioactive atom loses an alpha particle, the atomic number

A.  remains the same B.  increases by one

C.  decreases by two D.   decreases by four

32.   Infrared radiation cannot detected by

A.   a Geiger Muller tube   B.  A photographic film

C.  A flourescent paint  D.  A thermometer with a blackened bulb

33.  Which of the following circuit diagrams shows the correct positions for a lamp and a switch in a lighting circuit?

34.  A box is pulled horizontally with a force of 100N inclined at an angle of 50⁰ to the horizontal as shown in the figure below

The effective force in newtons is

A.  100/sin 50⁰   B.   100/cos50⁰  

C.  100 sin 50⁰   D.  100 cos 50⁰

35.   A block of mass 8kg slides on a rough horizontal surface under the action of a force of 48N as shown in the figure below

If the block moves with an acceleration of 5ms^-2, calculate the frictional force on the block

A.  6N B.  8N C.  40N D.  48N

In each of the questions 36-40, one or more of the given answers may be correct. Read each question carefully and then write the correct answer A,B,C or D according to the following

A. if 1,2,3only are correct

B. if 1,3 only are correct

C. if 2,4 only are correct

D. If 4 only is correct

36.   Loudness of a musical note depends on

1.  pitch 2.  velocity 3.  frequency 4.   amplitude

37.   Which of the following sentences is/are true about molecular theory of magnetism

1.  Breaking a magnet into two results into the formation of two magnets

2.  Heating and rough treatment destroys magnetism

3.  The poles of a magnet are of equal strength

4.  The lines of force t4ravel from a north pole towards a south pole

38.  Which of the following change(s) when water waves travel from a deep to a shallow region

1.   Velocity 2.   Amplitude 3.   Wavelength   4.  Frequency

39.  When reflection occurs in a plane mirror

1.  the image is real, erect and magnified

2.  the angle of reflection is equal to the angle of incidence

3.   the incident ray and reflected ray lie in different planes

4.  the object and the image are at the same distance from the mirror

40.   The components of electromagnetic spectrum have

1.  the same velocity 2.   different wavelength

3.  different frequencies 4.  the same refractive index for a given media

SECTION B (1993)

1.  The figure below shows the displacement-time graph for the motion of a body

(a)  sketch the speed-time graph for the motion (b) calculate the average speed for the journey

2.   A flask containing air is inverted into a beaker of water as shown in the figure below

(a)  state what is observed when the flask is gently heated and then allowed to cool.

(b)  Explain the observation in (a)

3.  (a)  (i)  What is meant by reverberation?

(ii)  How does complete absence of reverberation affect speech in a concert hall.

(b)  A girl produces sound waves near a series of regularly spaced reflecting surfaces. If the reflected are 15cm apart and the velocity of sound in air is 330ms^-1, calculate the frequency of the echo.

4.  (a)  Distinguish between potential energy and kinetic energy.

(b)  A block of mass 2kg falls freely from rest through a distance of 3m. find the kinetic energy of the block

5.  (a)  state two factors which affect the strength of an electromagnet.

(b)

The diagram above shows a small magnet placed near an electromagnet. Describe what happens to it when the key K is closed.

6.   (a)  A gold leaf electroscope is positively charged. State what happens when each of the

following is brought near the cap

(i)  a neutral metal

(ii)  a positively charged body

(b)  The figure below shows an arrangement for studying the effect of an electric field on moving particles and rays

Sketch on the above diagram the path taken by

(i)  alpha particles

(ii)   beta particles

(iii)  gamma rays

7.  1cm³ of oleic acid was dissolved in 999cm³of alcohol to form 1000cm³ of solution. A 1cm³ drop of the solution was put on a water surface sprinkled with lycopodium powder. The alcohol dissolved in the water leaving the acid to spread forming a patch of diameter of 28cm.

(a)  Calculate the volume of oleic acid in the 1cm³ drop of the solution.

(b)  Estimate the size of oleic acid molecule

(c)  Why was lycopodium powder used?

8.  (a)  What is meant by a first class lever?

(b)  Give two examples of first class levers.

(c)  By means of a lever, an effort of 50N moves a load of 200N through 3m. If the effort moves a distance of 16m, calculate;

(i)  the mechanical advantage

(ii)  the efficiency of the lever

9.

The diagram above shows rays of light in a semi-circular glass block.

(a)  Explain why ray AB

(i)  is not refracted on entering the block at A

(ii)  takes path BD on reaching B

(b)  Ray CB is refracted at B. calculate the angle of refraction(Refractive index of glass =1.5)

10.   Sketch the variation of potential difference with current for a thermionic valve.

(b)  *********

The above graph shows the variation of current with p.d across a device. Use the graph to find the resistance of the device

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