(Compulsory: Attempt all questions from this section)
Question 1.
a) Define work. When a body moves in a circular path, how much work does it do ? (2)
b) A body of mass 60 kg has the momentum 3000 kg m/s. (2)
Calculate the:
i) kinetic energy
ii) speed of the body.
c) In a three pin plug, why is the Earth pin made longer and thicker than the other two ? (2)
Question 2.
a) Draw a ray diagram to illustrate how a ray of light incident obliquely on one face of a rectangular class slab of uniform thickness emerges parallel to its original direction. Mention which pairs of angles are equal. (2)
b) The diagram below shows
an object AB placed on the principle axis of a lens L. The two foci of the lens are F₁ and F₂. The image formed by the lens is erect, virtual and diminished. Copy the diagram and answer the following questions : (2)
i) Draw the outline of the lens (L) used.
ii) Draw the ray of light starting from B and passing through O. Show the same ray after refraction by the lens.
iii) Draw another ray from B, which after passing parallel to the principal axis, is incident on the lens and emerges after refraction from it.
iv) Locate the final formed.
c) Why steam produced more burns than boiling water even both of them are at the same temperature. (2).
d) If the mechanical advantage of a machine is equals to its velocity ratio , what kind of machine is it ? Give the efficiency of the machine. (2)
Question 3.
a) An electric bulb is marked 220V, 100 W. The bulb is connected to a 220V supply.
Calculate
1. resistance of the filament.
2. current flowing through the filament. (2)
b) Is the filament resistance of a glowing bulb greater, smaller or the same compared to its resistance when it is not glowing ? Give reasons . (2)
c) State the energy changes which take place while using the following:
i) loudspeaker
ii) an electric cell. (2)
d) The ratio of the amplitude two waves is 3 : 5. What is the ratio of their intensities ? (2)
e) State the conditions for the formation of an echo and for resonance. (2)
Question 4:
a) State the principle of conservation of energy. (2)
b) Mention two factor that determine the rate of thermionic emission from a metal surface. (2)
c) A thorium isotopes ²³³Th₉₀ undergoes an α-decay and changes to radium. What is the atomic number and mass number of radium produced? (2)
e) Complete the equations :
1. ¹³¹₅₅I ---> X + ⁰₋₁e
2. ¹⁴₇N + ⁴₂He ---> O+ ¹₁H. (2)
Section B (40 marks)
Question 5.
a) The given diagram shows an arrangement of four pulleys. A load L is attached to the movable lower block and effort E is applied at free end of the string.
i) Copy the diagram and draw the arrows to indicate tension in each part of the string.
ii) Calculate the mechanical advantage of the system. (4)
b) The diagram shows the use of a lever. 
(3)
i) State the principle of moment as applied to the above lever.
ii) Given an example of this class of lever.
iii) If FA=10cm and AB= 500 cm, calculate the minimum effort required to lift the load.
c) A 30g of ice at 0°C is dropped into 100 g of water at 30°C. Calculate the final temperature of water when all the ice has melted. Given specific heat of ice= 80 cal /g, specific heat capacity of water= 1 cal/gC. (3)
Question 6:
a) The ray diagram given below
illustrates the experimental set up for the determination of the focal length of a converging lens using a plane mirror. (3)
i) State the magnification of the image formed.
ii) Write the characteristics of the image formed .
iii) What is the name given to the distance between the object and optical Center of the lens in the above diagram ?
b) The refractive index of air with respect to glass is defined as:
ᵍₐμ = sin i/sin r. (3)
i) Write down a similar expression for ᵍₐμ in terms of the angle i and angle R.
ii) In (i) above, if angle r= 90°, what is the corresponding angle i is called ?
iii) What is the physical significance of the angle i as in the part (ii) above ?
Question 7.
a)i) Define the phenomenon of resonance.
ii) Name the physical quantities whose SI units are:
1. Electron volt 2. Dioptre (3)
b) A stretched wire 0.5m long is made to vibrate in two different modes as shown in diagram below :
i) If the wavelength of the wave produced in mode A is 1m, what is the wavelength of the wave produced in mode B ?
ii) in which case is the note produced under louder ? Give a reason for your answer.
iii) inu which case is the pitch of the note produced higher ? Give a reason for your answer ? (3)
c) i) A woman years and echo of her voice from a distant hill after one second. What is the distance of hill from the woman. The speed of sound in air is 350 m/s.
ii) Give the approximate range of wavelength in vaccum associated with ultraviolet rays and visible light. (4)
Question 8
a) i) Write an expression for the resistance of a conducting wire in terms of length and area of cross section.
ii) Define the critical angle. How is the critical angle of a material related to its refractive index ? (3)
b) Two resistors of 3 Ω and 2Ω in parallel are connected to a Cell of emf 1.5V and internal resistance 0.3 Ω. Draw labelled diagram showing the above arrangement and calculate the current drawn from the cell. (3)
c) Name the principle on which functioning of a transformer depends .
ii) what is the function of the step-up of transformer ?
iii) can a transformer work it is connected to a D. C source ?
iv) diagram given below,
shows schemetically part of a step-down transformer.
Draw the complete diagram in your answer sheet . (4)
Question 9
a) State the energy changes in an AC generator. (1)
b) The graph given below shows it cooling curve of a substance which is being cooled. Answer the following questions :
i) What is the boiling point of the substance ?
ii) what happens to the region CB?
iii) why the region CB shorter than region ED ? (3)
Question 10
a) i) State the penetrating range of α, β- and γ-radiations.
ii) How are γ-rays produced ? (3)
b) A certain nucleus X has mass number 15 and atomic number 7. Find the number of neutrons. The X loses
i) one proton
ii) one β-particles
iii) one α-particle
Express each change and write the symbol of the new nucleus in each case. (3)
c) What is a nuclear reactor ? State its principle.
ii) Name a disease that is likely to be caused by an excessive exposure to α, β, γ rays. (3)
No comments:
Post a Comment