UNEB UCE PHYSICS PAPER 1 Oct./Nov. 1987

UNEB 1987

SECTION A

1.   An object is placed between the focal point and centre of curvature of a concave mirror. Which of the following fully describes the nature of the image formed?

A.  Real, inverted, diminished  B.  Real, inverted, magnified

C.  Real, erect, diminished D.  Virtual, erect, magnified

2.

Three identical lamps L₁, L₂ and L₃ just glow when connected as in the above figure. What will happen when a piece of copper wire is connected across L₁?

A.  L₁ and L₂ will go out  B.  L₂ and L₃ will glow brighter

C.  There will be no effect on the lamps D.  L₁ will be brighter than L₃

3.   When a force of 30N is applied to a trolley, the trolley moves through a distance of 10m in 20s in the direction of the force. The average power developed by the trolley is

 A.  6.67W B.  60W C.  15W D.  7.5W

4.

Two cells of e.m.f 1.5V and each having internal resistance of 2Ω are connected as shown above. Find the current, I, flowing in the circuit.

A.  3.00A B.  1.50A C   0.75A D  0.60A

5.

The figure shows a simple barometer. The height of the mercury column is 76cm. When the tube is slightly tilted, the height of the mercury column will

A.  be slightly higher than 76cm  B.  be lower than 76cm

C.  not change D.  oscillate about 76cm

6.   After 18hours, ¹/₁₆^th of the original mass of radioactive isotope remained. What is the half life of the isotope in hours?

A.  1.125 B.  3.6 C.  4.5 D.  9

7.   In an oil-film experiment to estimate the size of a molecule, 0.005cm³ of oleic acid was dropped on lycopodium powder on a water surface. The mean diameter of the acid was 5cm.The thickness of a molecule of oleic acid is

A. B.  

C.  π (2.5)²/0.005 D.  

8.   When a body is brought near a negatively charged electroscope, a decrease in divergence is observed. This may mean that the body is

(i)  positively charged

(ii)  negatively charged

(iii)  not charged at all

A.  (i), (ii) and (iii) B.  (i) and (ii) only  

C.  (i) and (iii) only D.  (i) only

9.

10.

11

12.  A bullet is fired vertically upwards from the ground. If it reaches its maximum height in 4s, find the total distance it covers by the time it hits the ground.

A.  40m  B.  80m

C.  160m  D.  280m

13.   A sound wave of frequency 250Hz is produced 350m away from a high wall. If an echo is received after 2s, the wavelength of the sound wave is

A.  2.4m  B.  1.2m

C.  0.83m  D.  0.6m

14.   When liquid naphthalene is cooled, a time comes when its temperature remains constant for some time. This is because naphthalene freezes when

A.  it stops losing heat

B.  the heat lost to the sorroundings is replaced by the latent heat of fusion

C.  an insulating layer forms around it

D.  it loses as much heat as it gains from the surroundings

15.   Which of the following statements about boiling and evaporation is correct?

A.  Boiling takes place at all temperatures while evaporation does not

B.  Evaporation takes place throughout the liquid while boiling takes place at the bottom of the container

C.  Boiling takes place throughout the liquid while evaporation takes place at the surface

D.  Evaporation takes place at lower temperature than boiling does

16.   Which of the following is the correct sequence showing conversion of energy in an X-ray tube?

A  Electrical energy → heat energy → kinetic energy → electromagnetic energy

B.  Heat energy → electrical energy → kinetic energy → electromagnetic energy

C.  Electrical energy → heat energy → electromagnetic energy → kinetic energy

D.  Electrical energy → heat energy → kinetic energy → electromagnetic energy

17.  Two wooden blocks X and Y are placed in contact with asmooth table as shown below.

The mass of X is twice the mass of Y. If a constant force acts on X, then

A.  the acceleration of X will be twice that of Y  

B.  X and Y will have the same acceleration

C.  the acceleration of X will be half that of Y  

D.  both will move with uniform velocity

18.

When a magnet is moved relatively to the coil as shown above, the magnitude of the induced current will not be increased by

A.   moving the magnet faster B.   using the coil with more turns

C.   using a more sensitive galvanometer  D.   using a stronger magnet

19.   A mass of 0.20 kg produces an extension of 6 cm in a spiral spring. The force required to produce an extension of 1cm is

A.  (0.20x6x10)N   B.  (0.20×10/6)N

C.  6x D.  6x

20.

The above figure shows the magnetic field pattern around two wires P and Q carrying a current perpendicular to the plane of the paper. Which of the following statements is true?

A.  Current in P is flowing into the page while that in Q is flowing out of the page.

B.  Both currents in P and Q are flowing into the page

C.  Both currents in P and Q are flowing out of the page

D.  Current in Q is flowing into the page and that in P is flowing out of the page

21.  The critical angle of glass is 42⁰. Which of the diagrams describes the path of light at critical angle?

22.   Which of the following statements are true about X-rays?

(i)  X-rays are the cause of photoelectric emission  

(ii)  X-rays are deflected by an electric field

(iii)  X-rays ionize matter

A.  (i), (ii) and(iii) B.   (i) and (ii)  

C.   (ii) and (iv)  D.  (i), (ii) and (iii)

23.

Three forces act on a body as shown in the above figure. If the forces are in equilibrium, calculate F

A.  20N B.  14N C.  10N D.  3.7N

24.   A machine lifts a load of 5000N through a distance 0f 10m in 5s. The average power of the machine is

A.  0.1kW B.   10kW C.  50kW D.  250kW

25.   Which of the following graphs describes uniformly accelerated motion

26.  Parallel rays can be obtained practically from a point source of light if the source of light is placed at

A.  the principal focus of a concave mirror  

B.  the centre of curvature of a concave mirror

C.  the principal focus of a convex mirror

D.  the centre of curvature of a convex mirror

27.

A brick of mass 2kg is lifted to a height of 3m along a smooth, inclined plane 5m long, as shown above. The work done is

A.  10J B.   60J C.  6J D.  100J

28.   Thermionic emission may occur when

A.  fast moving electrons hit a metal B.  a metal is given heat energy

 C.  metal receives light energy D.  a substance undergoes radioactive decay

29

The total resistance in the above circuit is

A.  0.8Ω B.  5.0Ω C.  8.0Ω D.  1.25Ω

30.  Arrange the following radiations in order of decreasing frequency

 A.   Gamma rays, x-rays, light, radiowaves  

B.  radiowaves, light, gamma rays, radio waves

C.  x-rays, light, gamma rays, radiowaves

D.  radiowaves, light, gamma rays, x-rays

31.

A uniform metre rule is suspended with a string at the 20cm mark and is kept horizontal by a mass of 120kg from one end as shown above. Find the mass of the metre rule

A.  80g B.  30g C.  24g D.  120g

32.   The circuit below shows diodes and bulbs connected to a d.c supply

Which of the following pairs of bulbs will light up?

A.  M and N  B.  N and H C.  M and L D.   H and L

33.   Which of the following statements about eclipses is NOT correct?

A.  During the eclipse of the sun, the shadow of the moon falls on the earth

B.  During the eclipse of the moon, the earth is between the sun and the moon

C.  During the eclipse of the sun, the moon is between the sun and the earth

D.  During the eclipse of the moon, the shadow of the moon falls on the earth

34.  The below diagrams show two capillary tubes standing in a trough of mercury and two capillary tubes standing in a trough of water.

Arrange the tubes in order of increasing height of the liquid column.

A.  (i),(ii),(iv),(iii)     B.  (ii),(i),(iv)(iii)  

C.  (ii),(iv),(i),(iii) D.  (iii),(iv),(ii),(i)

35.  The diagram below shows the electric field pattern of charged bodies X and Y.

Identify the charges on the bodies

36.   Find the efficiency of a machine which requires an effort of 200N to raise a load of 18000N if its velocity ratio is 300

A.  30% B.   60% C.  67% D.   90%

37.  

Name the colours of the overlapping patches K,L,M, and N of primary colours

38.   A driver uses a convex mirror as his driving mirror because it

(i)  forms an upright image (ii)  gives a bigger magnification  

(iii)  gives a wider field of view

A.  only (i)  B.  only (i) and (ii)  C.  only (iii)  D.  All (i),(ii),(iii)

39.   The diagram below shows drops of liquids X and Y carefully put on a clean sheet of flat glass.

Which of the following statements does NOT explain why the drops take different shapes?

(i)  The force of attraction between molecules of X is less than that between molecules of Y

(ii)  The force of attraction between molecules of Y and glass is less than that between molecules of Y

(iii)  The force of attraction between molecules of X is less than that between molecules of X and glass

(iv)  The force of attraction between molecules of Y and glass is greater than that between

molecules of Y

A.  only (i)  B.  only (i) and (ii)  C.  only (iii)  D.  only (i),(ii),(iii)

40.   Forces of 50N and 400N are applied to pistons A and B respectively as shown below.

The areas of cross-section of A and B are 2 x 10^-4 m² and

8 x 10^-2m² respectively. Which of the following is not true?

A.  Both pistons A and B remain at the same level  

B.  The upthrust on piston B is equal to 20000N

C .  The pressure exerted on the water by piston B is 5×10⁴Nm^-2

D.  Piston B is going to move upwards

SECTION B.

1.   10³kg of water falls through a height of 15m every second to operate an electrical generator

(a)  The power input to the generator is…

(b)  Give any two possible reasons why the efficiency of the generator is less than 100%

2.

The diagram above shows the arrangement for the Brownian motion experiment.

(a)  Describe what would be seen through the microscope

(b)  What would be observed if the temperature of the smoke cell was increased?

3.  (a)  What is the difference between atomic number and mass number?

(b)  The half-life of iodine is 8 days. Find the mass which will have decayed in 32 days if the initial mass is 1.6kg

4.   (a)  Draw a labeled ray diagram to show the formation of an image in a pin-hole camera.

(b)  State the effect on the image on a pin-hole camera of

(i)  enlarging the pin-hole

(ii)  decreasing the distance between the pin-hole and the film.

5.  A battery of e.m.f 24V is connected in series with a resistor R and a lamp rated 10V, 20W as shown below.

If the bulb is operating normally, find

(i)  the p.d across the resistor

(ii)  the value of R

(iii)  the power dissipated in the resistor

6.   Sketch the magnetic field pattern between the N and S poles in the figure below

7.   (a)  Define

(i)  critical angle

(ii)  total internal reflection

(b)

A ray of light traveling from air is refracted as shown above. If the refractive index of glass is 1.5, calculate the value of angle i

8.  The diagram shows the main parts of a cathode ray oscilloscope (CRO).

(a)  Name the parts labeled P,Q,R,S

(b)  State two uses of CRO

9.  (a)  Name three constituents of concrete materials

(b)  State any two characteristics of concrete which make it a desirable building material

(c)  State any three ways in which concrete may be reinforced

10.  A uniform metre rule with a 200g mass suspended at the zero mark is balanced on a knife when pivoted at the 18.0cm mark as shown below.

(a)  Calculate the mass of the metre rule

(b)  If the 200g mass was placed at the 5.0cm mark, where would the knife edge be?

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