2) What is a pure spectrum of light ? (2)
a) How much force will be needed to lift a drum into the truck directly, without using the plank. (Take g= 10 m/s²)? (1)
a) The diagram only Shows one lead from the battery to each bulb, but a complete circuit most have two. How does the current get back to the battery ? (2)
3) Distinguish between a real and a virtual image. (2)
4) Show , using a ray diagram, how a converging lens can be used to form a virtual image. (2)
5) What is the difference between forced and natural vibrations ? (2)
6) With the help of simple diagram, show that mechanical advantage of a single fixed pulley is 1 and that of a single movable pulley is 2. (2)
7) Give one advantages and one disadvantage of connecting electric cells in parallel. (2)
8) How much does it cost to run one heater of 1000 W and two electric bulbs of 40 W each for eight hours if one unit of electricity cost Rs2. (2)
9) Why is it dangerous to use wet hands to put off a switch ? What purpose does a fuse serve in a circuit ? (1+1)
10) What is the source of sun's energy ? Which element give rise of this energy? (1+1)
11) Give two properties of X-rays. (2)
12) State two factors that effect the fundamental frequency of vibration of a stretched string. (2)
13) A Truck driver can load oil drums into the back of the truck by pushing them up a sloping plank or lifting them directly. Each drum has a mass of 80 kg., the plant is 3m long and back of the truck 0.8m above the ground.
b) How much energy would be converted in lifting drum into the truck without the plank ? (2)
c) if the force needed to push a drum up the plank is 300N, why is this less than the answer to part (a)? (2)
d) When the truck is loaded, the driver drives off. List the major energy changes that take place in moving the truck . (3)
e) The driver has to stop at the factory gates . What happens to the kinetic energy of the truck ? (2)
14) Difference between the following:
a) noise and a musical note.
b) frequency and wavelength of sound. (4)
15) The human ear can detect continuous sounds in the frequency range 20 Hz to 20000 Hz. Assuming speed of the sound in air is 330 m/s for all frequencies , calculate the wavelength corresponding to given extreme frequencies of the range. (2)
16) Give reason for the following:
a) The same musical note when played on a piano and played on a flute sounds different. (2)
b) Soldier often March 'out of step' while crossing bridges. (2)
17) The diagram shows a part of electrical system which operates some of the lights.
b) if a car owner adds extra lights to the car, why must the paint be removed from the body-work where the electrical contact is made ? (2)
c) The two rear lights wired up incorrectly, and only light faintly.
i) why do they only light faintly?
ii) Draw a diagram to show how the wires should be connected to make the lights work normally. (2)
d) There are four side lights, and a number plate light (i.e., a total of five lights). Each bulbs is labelled 12V, 4W
i) what does the label mean ?
ii) How much current flows through each bulb (assuming it is connected properly)?
iii) How much current does the battery supply to these bulbs altogether (i.e., in total)? (3)
e) If the lights are on, they go dim when the car is started. Why is this? (2)
18) a) Which would be the worse , the burn you get holding your hand in a jet of steam or that got from boiling water, both at 100°C ? Give a reason for your answer. (2)
b) In an experiment to measure the specific heat capacity of brass, 0.2 kg of hot water, at a temperature 65°C, was poured into a heavy brass container of mass 1.5 kg, initially at 15°C. After stirring, the final temperature reached was 45°C. Assume that the specific heat capacity of water is 4200 J/kg/°C.
i) Calculate the heat energy released by the hot water in cooling from 65° C to 45°C.
ii) Assume that the heat energy calculated in part (i) is given by the brass container in raising its temperature from 15°C to the final common temperature of 45°C. Calculate the heat energy observed by the brass container per °C rise in temperature.
iii) Using the result obtained in part (ii), calculate the specific heat capacity of brass. (5)
19) After robbery, if a window has been broken there will be tiny particles of glass. Some of these will be found at the scene of the crime and some maybe caught in the thief's clothing. If the police can prove that these particles are identical, they have a strong case.
A method of doing this is to suspend the particles of glass in a special liquid. Light of a single colour is shone through the liquid and the particles viewed through a microscope. The temperature of the liquid is then slowly altered . This alters the speed of light through the liquid (i.e., it alters the refractive index). At one particular temperature the particles of glass disappear. If this happens at the same temperature for both sets of glass particles , they probably came from the same broken pane of glass.
a) Complete a copy of the diagram to show how light bands when it travels from the liquid to the glass and black to the liquid,
i) if the lights slows down in the glass.
ii) if the light speeds up the in the glass. (4)
b) why is the light used in the police work a single colour ? (2)
c) Under what two circumstances can light moving from a liquid to glass pass straight on without bending ? (2)
d) When do the particles of glass disappear in the police method ?
20) The emmission of an α-particle or emission of β-particle is nearly always accompanied by what is known as γ-radiation.
i) How does the ionising power of γ-radiation compare with that of α- and β-particles ?
ii) Is γ-radiation more or less penetrating then α- and β- particles?
iii) Is it possible to deflect γ- radiation in the ways that α and β-particles can be deflected, using electric or magnetic fields ?
iv) What is γ-radiation thought to be ? (4)
b) Radium- 226 (²²⁶Ra₈₈) is radioactive and emits α-particles.
i) By how much does the atomic number of a radium nucleus (²²⁶Ra₈₈) change when an α-particle is emitted ?
ii) By how much does the mass number of the radium nucleus in part (i) change?
iii) The new nucleus formed, when a nucleus of (²²⁶Ra₈₈) emits an α-particle is identified as a nucleus of another element fairy close to radium in the periodic table. Identify this element from the data: Polonium (Po₈₄), Astatine (At₈₅), Radon (Rn₈₆) and Francium (Fr₈₇). (3)
c) State three major uses of X-rays. (3)
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