# MWANZA REGIONAL FORM SIX JOINT EXAMINATION- 2020 CODE NO. 131/2 – PHYSICS 2

PRESIDENT’S OFFICE

MWANZA REGIONAL

FORM SIX JOINT EXAMINATION- 2020

###### Tangazo

CODE NO. 131/2 PHYSICS 2

TIME 3:0 HOURS

INSTRUCTIONS:

1. This paper consist of ONLY ONE section with a total of SIX (06) questions.
3. Each question carries twenty (20) marks.
4. Mathematical table non programmable calculators may be used.
5. Cellular phone are not allowed in the examination room.
7. The following information’s may be useful.
1. Acceleration due to gravity g = 9.8ms2.
2. Pie π = 3.14.
3. Density steel = 7800kg/m3
4. Speed of light , c= 3x 108m/s
5. 1      = 9×109NM2C2

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6. Change of electron = 1.6×10-19C
7. Permeability of free space µo =4π 10-7HM-1
8. Permittivity of free space 8.85 x 10-12FM-1
9. Young’s modules of stree wire 210 x 109NM2
10. Young’s modulus of copper wire 117 x 109NM2.
11. Avogadro’s Number = 6.02 x 10 23
12. plank’s constant h=6.63 x 10-34 Js
13. 1 ev = 1.6×10-19J
14. Density of mercury = 13600kg/m-3
15. Density of water = 1000kgm-3.
16. IU = 93/Mev
17. Mass of x – particle 4.0026U
19. Standard Pressure = 1 atm = 760 mmHg = 1.013 x 105Nm-2
20. Molar mass of oxygen. M = 32gmol-1
21. Molar gas constant, R = 8.3Jmo-1K

1. (a)     (i)    State Bernoulli’s Principle of flow in terms of energy        (01 marks)

(ii)     From Newton’s second law motion, derive Bernoulli’s equation for the fluid flowing steadily in the horizontal pipe                (04 marks)

(b) (i) Children are told to avoid starting too close to rapidly moving train because they

might get sucked under it. Is this possible? Explain.            (2 ½ marks)

(ii)    A simple garden syringe used to produce jet of water consists of a piston of area 4cm2 which moves in horizontal cylinder which has a small hole a area 4mm2 at its end. If the force on the piston is 50N. Calculate the volume for the speed at is neglible                                 (4 marks)

(c)     (i)     Define ” terminal velocity ” in term of fluid mechanics        (01 marks)

(ii)    According to Bernoulli’s theorem, the pressure of water should remain uniform in

In a pipe of uniform cross section. But actually it goes on decreasing. Is so why?.                                        (2.5marks)

(iii)      Two tubes AB and BC of the same length and having radii 2mm and 1mm

Respectively are joined end to end at B. A liquid flows through them and the

Difference in pressure between A and C is 340 mmHg. What is the difference in

pressure between B and C?. (05 marks)

1. (a)     (i)    Briefly explain three the types of damped oscillations        (03 marks)

(ii)    Outline any three differences between progressive waves and stationary wave

(03 marks)

(iii)    A progressive wave equation is given by:-

y = A sin (wt + kx) what do the following terms represent wt, kx(wt+kx)

and Sin (wt +kx)                            (02 marks)

(b) (i)      Explain the colours seen in soap                    (02 marks)

(ii)    When newton’s rings are observed with air between the spherical surface of lens and a

Plane glass sheet, the diameter of the length dark fringe is 12mm. when a Liquid is introduced between the spherical surface and the plane surface, the diameter of the tenth dark ring becomes 10.2mm. What is the refractive index of the liquid?    (04 marks)

(c) (i)    What is Doppler effects? Mention any two uses of Doppler effect (2 marks)

(ii)    The Doppler effect using sound waves of frequency 2.25 x106 Hz is used to monitor the heat best of a fetus. A maximum beat frequency of 600Hz
is observed. Assuming that the speed of sound in tissue is 1.54 x 103m/s .calculate the maximum velocity of the surface of beating heart
(04 marks)

1. (a) Define the following terms
1. Tensile stress
2. Tensile strain

(03 marks)

(b)     A copper wire 2.0m long and 1.22 x 10-3m diameter is fixed horizontally to two rigid supports 2.0m part. Find the mass in km of the Load, which when suspended at the midpoint of the wire produces sag of 2.0 x 10-2 m at the point.        (06marks)

(c ) (i)     Explain the fact that the legs of a mouse are thinner than those of an elephant yet

the weight of each animal is a well supported by legs of animals.     (02 marks)

(ii)     A lord of 500kg is having from steel wire. If its length is 3cm and cross section area 2x 10-1cm2 was found to stretch the wire by 4 x 10-1cm above its normal length, what are the stress and young’s modules of the wire? (06marks)

(d) With the help of diagrams give the meaning of shear strain and shear stress.

(03 marks)

1. (a) (i)     Define electric field intensity, E.      (01 mark)

(ii)     Give two possible units in which E can be measured.          (01 mark)

(iii)     Show that the two units in 6. (a)(ii) are equivalent.     (03 marks)

(b) (i) A charged rod attracts bits of dry cork dusts which, after touching the rod, often

jump violently away from it. Explain.         (03 marks)

(ii) Two identically charged spheres attract each other with a force of 0.108N when

placed with theirs centers 0.5m apart. The spheres are brought into contact for

some time and then returned to their initial position. It is found that they norepel

each other with a force of 0.036N. Calculate the initial charges on each sphere.

(06 marks)

(c)     In a small Van de Graff machine the metal sphere reaches a potential of 2.4×105V

before it discharges by sparking across an air gap.

(i)     If the sphere is of radius 0.15 m, calculate the charge on the sphere just before

discharge.      (03 marks)

(ii)     What is the electric field at the surface of the sphere just before the discharge takes place? (03 marks)

1. (a) (i) Define intensity of magnetization and magnetic susceptibility.     (03 marks)

(ii) With the aid of the diagram explain what is meant by the term hysteresis.

(04 marks)

(iii) Differentiate between magnetically soft and magnetically hard materials.

(04 marks)

(b) An iron ring of mean diameter 10 cm is uniformly wound with 2000 turns of a wire.

When a current of 0.25 A is passed through the coil, a flux density 0.4 T is set up in the

iron. Find;

(i) The magnetic force.      (03 marks)

(ii) The relative permeability of the iron under these conditions.     (02 marks)

(c)     A car aerial is 1.5 m long. Calculate the e.m.f across it when the car is travelling at 30m/s

in an east-west direction. The horizontal component of the Earth’s field if 18µT. Assume

that the aerial is vertical.     (04 marks)

1. (a) (i) Write down Einstain’s photoelectric equation and explain the symbols used

(02 marks)

(ii)    The frequency of incident radiation on a metal surface is 5 x 1014 Hz and electrons with maximum energy of 2.3 10-19J are emitted. What wavelength of incident radiation is required to liberate electrons with maximum energy of 5.6 x 10-19J?                                     (07 marks)

(b)    Some energy levels or a mercury atom are shown below

Level__________________________________ 0Energy in Ev

4__________________________________ -1.6

3__________________________________ -3.7

1__________________________________ -5.5

1__________________________________-10.4

Calculate:-

1. The ionization energy of a mercury atom in Joules            (02 marks)
2. The wavelength of radiation emitted when an electron moves from level 4 to level 2

(03 marks)

(c)     Explain what is meant by the wave – Particle duality. Howa are the two aspects related

(02 marks)

(d)     Calculate the Broglie wavelength of

1. An electron with K. E of 54eV                    (02 marks)
2. A 4g golf ball travelling with a speed of 2m/s            (02marks)

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