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in warming the house, cooking, heating the water and drying the washed clothes. 7. Biogas Activity 5.19 (Work in groups) To conduct research on how to produce biogas Materials: bio-digester, reference materials (including this book), internet 1. Using reference materials (including this book) or internet, research abo... |
energy. This chemical energy is released when wood burns and it’s converted into heat and light energy. 143 (iv) Food – the chemical energy in food is released while the food is being digested. As the bonds between the atoms of the food break, new substances are created and chemical energy is given out. Warning Subjec... |
exhausting them are called renewable resources. (a) Renewable energy sources A renewable energy source is an energy source which can’t be depleted/exhausted. They exist infinitely i.e. never run out. They are renewed by natural processes. Examples include; (i) Sun However, some like trees they can also be depleted, li... |
� energy source. All energy sources have atleast an effect to the environment. Some energy sources have a greater impact than others. Energy is mostly lost into the environment in form of heat and sound. The following are some of the effects of use of the energy sources to the environment: • air and water pollution • c... |
is renewable and have less effect to the environment. With your help we can support projects that help to train and educate forest communities so that they can use forests in a sustinable manner and protect their livelihoods for years. (d) Land degradation Land degradation is the process in which the value of bio-phys... |
while an electrical heater is on, you may get an electrical shock. From your discussion, you should have observed that the water in the basin boils. Electrical energy has been converted to heat energy which boils the water. When the radio was connect to the socket and turned on, electrical energy is converted to sound... |
to run. A microphone changes electric energy to sound energy and so on. One other example of energy transformations occurs when lightning strike. If it hits a tree, it’s electrical energy will be changed to heat and thermal energy. The tree will become hot and can even burn as a result of electric discharge, it can sp... |
be created or destroyed but is simply converted from one form into another. Or in other words we can state it that in a closed system the total amount of energy is conserved. Energy can be inter-converted among many forms, mechanical, chemical, nuclear, electric, and others but the total amount of it remains constant.... |
A and E. What do you notice aboue the heights? 5. Repeat the activity with point A at a lower vertical height. 6. What type of energy does the ball bearings possess at points A, B, C, D and E. 7. Compare and comment on the total amount of energy possessed by the ball bearing at points A, B, C, D and E. 8. Make a concl... |
energy is constant (conserved). That is kinetic energy + potential energy = constant. Therefore, mechanical energy has been conserved. (b) A body thrown upwards Activity 5.26 To demonstrate the law of conservation of M.E using a ball thrown upwards (Work individually) Materials: tennis ball Steps 1. Throw a tennis bal... |
) the kinetic energy of the pendulum bob the most. the potential energy of the pendulum bob the least. 2. State the following laws: (a) (b) law of conservation of energy law of conservation of mechanical energy. 3. Describe how mechanical energy is conserved. 5.12 Ways of conserving energy Activity 5.27 (Work in groups... |
buying minimally packaged goods, choosing reusable products over disposable ones, and recycling. Use 30% to 50% less paper products, 33% less glass and 90% less aluminum. (vi) People who live in colder areas should super insulate your walls and ceiling. It can save your the electricity of heating or fire wood costs. (... |
of the stove required. Mark arc AB which represents the circumference of the mouth of the charcoal burner. Draw AO and OB. Draw arc CD. The radius OD will depend on the area of the base on which the charcoal is to rest. Cut the section ACDB. Assembly Fold the plate ACDB in a shape of a cone as shown in Fig. 5.27(b). R... |
open jerry can Fig. 5.30: Heat collector Heat exchanger Use another 20 litre jerry can (Fig. 5.31) and open at the top to allow the pipes to enter and then seal it using the same material and a hot object. The hot object will make the materials to fuse together. Make provisions for water to enter and leave the heat ex... |
SI unit. 2. A motor raised a block of mass 72 kg through a vertical height of 2.5 m in 28 s. Calculate the: (a) work done on the block. (b) useful power supplied by the motor. 3. A person of mass 40 kg runs up a flight of 50 stairs each of height 20 cm in 5 s. Calculate: (a) the work done. (b) the average power of the... |
which positions does the monkey have the least energy? What name is given to this type of energy? (d) What type of energy would the moneky have if it stopped swinging but still hanging? 165 11. A device which converts one form of energy to another is called a transducer. Name one transducer in each of the cases energy... |
of good into the ships for export, joining of timber and metal using screws, splitting of firewood using a wedge, digging a garden in preparation for planting, lifting heavy objects into tracks. The devices that help us to perform work easily are called machines. Machines can either be simple or compound. In topic 3, ... |
that is applied is called the effort (E) and the force the machine must overcome is called the load (L). Note that both the load and effort are forces which act on the machine. 6.2 Mechanical advantage, velocity ratio and efficiency of machines Activity 6.2 (Work in groups) To investigate and determine mechanical adva... |
there is no such a machine because some energy is wasted in overcoming friction and in moving the moveable 171 parts of the machine. Hence, more energy is put into the machine than what is output by it. Thus, Work input = Useful work done + Wasted work done To describe the actual performance of a machine we use the te... |
Steps 1. Now, access the internet and reference books and conduct research on classification of simple machines. 2. Classify simple machines 3. Discuss your findings with other groups in your class. Simple machines are classified into two groups i.e. force multiplier and distance or speed multipliers. Force multiplier... |
hammer (d) Pliers Fig. 6.2: Pivot between the load and the effort 2. Second Class: The load is between the effort and the pivot. Examples (Fig. 6.3). Load Effort Pivot Load Pivot Effort (a) Wheelbarrow (b) Bottle opener Fig. 6.3: Load between efforts and pivots 175 3. Third class: The effort is between the load and th... |
(a) Mechanical advantage = (b) Efficiency = M.A V.R = 3 4 = 75% Example 6.5 load effort = 450 N 150 N = 3.0 × 100% A worker uses a crow bar 2.0 m long to lift a rock weighing 650 N (Fig. 6.7). 650 N x ( 2 – x ) m 250 N Fig. 6.7: Crow bar (a) Calculate the position of the pivot in order to apply an effort of 250 N. (b)... |
1. Attach a spring balance on the trolley. Place a piece of wood in the trolley. 2. Pull the piece of wooden from the ground vertically upwards using the spring balance. Record the force reading on the spring balance. 178 h (a) A piece of wood moved vertically upwards through (h) s (b) Moving the load along the slope ... |
to frictional force. The effect of length of an inclined plane on its mechanical advantage Activity 6.6 To investigate how the length of an inclined plane affects its mechanical advantage Materials: A trolley, inclined plane, masses Steps 1. Measure the mass of a trolley. Place it on an inclined plane of length l, (Fi... |
Repeat the above steps using a bolt and a nut (Fig 6.12). 11. Discuss your findings with other groups in a class discussion. Fig 6.12(a) shows a screw, bolt and nut. Nut Bolt Top view Pitch Screw Bolt Fig. 6.12 (a): Screws, bolts and nut The distance between the two successive threads is called pitch. When the screw i... |
the two cases. 5. Which feature of the set-up represent the wheel and axle? 6. Observe the setup from B and draw the wheel, axle, load and effort. 7. Using various loads, find the force which in each case will just raise the load. Record your results in tabular form as shown in Table 6.2 below. Load Effort M.A Table 6... |
or rim. Pulleys are used to change the direction of a force and make work easy. There are three types of pulleys i.e. single fixed pulley, single movable pulley and block and tackle. (a) Single fixed pulley Fig. 6.16 shows a single fixed pulley being used to lift a load. This type of pulley has a fixed support which d... |
two pulley sets. One set is fixed and the other is allowed to move. The pulleys are usually assembled side by side in a block or frame on the same axle as shown in Fig. 6.19 (a). The pulleys and the ropes are called the tackle. To be able to see clearly how the ropes are wound, the pulleys are usually drawn below each... |
of strings sections supporting the load. Precaution: The weight of the block in the lower section of the system has to be considered as this increases the load to be lifted. Mechanical advantage of a block and tackle Activity 6.11 (Work in groups) To determine the mechanical advantage of a block and tackle Materials: ... |
100% 200 N (a) 210 N Fig. 6.23: Pulley system (b) = 66.7% (b) (i) velocity ratio = 5 (ii) mechanical advantage (iii) efficiency = load effort = 210 N 60 N = 3.5 = 3.5 5 × 100% = 70% Example 6.7 Draw a diagram of a single string block and tackle system with a velocity ratio of 6. Calculate its efficiency if an effort o... |
load of 600 N, if the system is 65% efficient. 4. A pulley system has a velocity ratio of 4. In this system, an effort of 68 N would just raise a load of 216 N. Find the efficiency of this system. Topic summary • A machine is a device that makes work easier. • Mechanical advantage (M.A) is the ratio of load to effort.... |
, carries it horizontally then up a ramp of length 6.0 m onto a pick-up and finally drops the bag of cement on the pick-up (Fig. 6.27). Fig. 6.27: Worker lifting cement on the pick-up (a) Explain the energy changes in the various stages of the movement of the worker. (b) During which stages is the worker doing work on ... |
.A. (c) Find the efficiency. 15 000 N 20 000 N Fig 6.31: Single fixed pulley 2.0 x 104 N Winding machine 3.2 × 104 N Fig. 6.32: A winding crane 10. Fig. 6.33 shows a pulley system. (a) What is the velocity ratio of the system? (b) Calculate the efficiency of the system. (c) Show the direction of the force on the string... |
to transmit radio and television signals. In this unit, we shall study the production of waves and some common terms and properties used in describing wave motion. By understanding more about waves, more uses are made of them. The study of waves begin with the concept of oscillations. 7.1 Oscillations Movements form a... |
A One oscillation is the movement A. C B B A Vibrationg String The amplitude is the distance BA or BC. B!"#$%&'"()"*"+ Fig. 7.3: A clamped rule A T a a 199 t3 Time t4 t1 a t2 Displacementtime graph!"#$%&'"()"*"+.1.2 Factors affecting oscillations Activity 7.1 (Work in groups) Materials: Bob, stand, string To investig... |
slower the ruler swings. (b) the longer the ruler, the slower it swings. All the above activities indicate that the frequency of a vibrating system is affected by: (a) Length – the longer or larger the body the lower the frequency e.g a shortened guitar wire produces higher pitch. (b) Mass – the bigger the mass /thick... |
(Work in groups) To demonstrate the formation of pulses using a rope Materials: Rope, pins, nails, helical springs and table Steps 1. Fix one end of a rope to a wall. Hold the free end of the rope so that the rope is fully stretched. 2. Quickly move your hand upwards and then return to the original position as shown i... |
that do not require a medium to travel from one point to another. They can travel through empty space (vacuum). Examples of electromagnetic waves are X-rays, gamma rays, visible light etc. They are produced by electric and magnetic fields. Mechanical waves These are waves which require a medium to travel from one poin... |
wave motionfixed endslinky spring (b) Key: C - Compressions R - Rarefaction Fig. 7.12: Longitudinal wave Thus, a longitudinal wave consists of compressions and rarefactions. Compressions is a region on a longitudinal wave with a high concentration of vibrating particles. On the other hand rarefaction is a region of th... |
7.14 shows a graph of displacement of particles against time. We see that the particles of the rope just vibrate up and down about their mean or rest position, but do not move with the wave. The disturbance is transferred from particle to particle. The distance travelled by the disturbance (wave energy) during each pe... |
for one vibration /oscillation. It is also the time taken to cover a distance of one wave length. Thus, the value of T in Fig. 7.17 is the periodic time. By definition, periodic time is the duration for one complete oscillation. Amplitude, (A) As a body or particles vibrate, they change position from the mean rest pos... |
Frequency × wavelength The equation v = fλ is called the wave equation. This formula holds for all waves. 210 Example 7.1 A slinky is made to vibrate in a transverse mode with a frequency of 4 Hz. If the distance between successive crests of the wave train is 0.7 m calculate the speed of the waves along the slinky. So... |
c) frequency (d) wavelength 212 Solutions (a) 0.3 cm (c) f = 1 T = 2.5 Hz (b) T = 0.4 s f = 2.00 (d) λ = 2.5 v = 0.8 m Example 7.7 A spring vibrates at the rate of 20 cycles every 5 seconds (a) Calculate the frequency of the waves produced. (b) If the wavelength of the waves is 0.01 m, find the speed of the waves. Solu... |
. (a) Determine the: (i) Frequency of the wave. (ii) Period of the wave. (iii) velocity of the wave. (b) Determine the time taken by the generated waves to hit a barrier that is 250 m away from the wave. 12. Using specific properties of light, explain why it is a transverse wave. 13. Define the following terms and stat... |
are in phase in a wave motion. 215 • A ray is a line draw to show the direction of travel of wave energy and is perpendicular to the wavefront. • Water and sound waves like light waves, obey the laws of reflection. Topic Test 7 1. Two waves that are in phase, they form a type of interference called _____. A. Construct... |
.22 m braodcasting on the frequency 88.5 kHz. 10. (a) Give the meaning of the symbols in the equation v = f λ. (b) Calculate the wavelength of a wave if the speed is 45 m/s and the frequency is 5 Hz. 11. Radio wave travel with a speed of 3 × 108 m/s in air. If a radio station broadcasts at a wavelength 125 m, calculate... |
to touch a small pith ball suspended by a thread (Fig. 8.2) and see what happens. Prongs 3. What makes the tuning fork vibrate? Fig. 8.2: Vibrating tuning fork displaces a pith ball. 4. Dip the vibrating prongs in water in a container and observe what happens. 5. What happens to water immediately the fork is dipped in... |
layer passes the energy to the next layer of air molecules and returns to the original position. Thus a region of compressions moves to the right (Fig. 8.5(c)). As prong X moves to the left, a region of reduced pressure or a rarefaction is produced in the vicinity of (Fig. 8.5(d)). The compressed air in the next layer... |
to the middle ear. The ear canal channels the waves to the eardrum. The eardrum is a thin, sensitive membrane stretched tightly over the entrance of the middle ear. The waves cause the eardrum to vibrate. It passes these vibrations to the hammer which is one of the three bones in the middle ear. The hammer vibrates ca... |
of sources of ultrasonic sound is ship siren and some factory sirens. Therefore, ultrasonic sound has a fundamental frequency that is above the human hearing range i.e. sound with fundamental frequency above 20 000 Hz. The reverse of ultrasonic wave is the infrasonic. Infrasonic is a wave in which the fundamental freq... |
speed of sound in water is 1 500 m/s, how deep is the water? Data: Time taken = 1 s; speed, v = 1 500 m/s for to and fro Solution Time taken for sound to reach the seabed = t 2 = 1 2 = 0.5 s From; v = d t or use v = 2d total time d = v × t = 1 500 m/s × 0.5 s = 750 m Exercise 8.1 1. Define the term sound. 2. Describe ... |
2.5 seconds and the second one after 4.5 seconds. Determine: (a) The velocity of sound. (b) The separation distance “y”. 226 8.6 Characteristics of sound waves The three main characteristics of musical sounds are: (a) Pitch It is the characteristic of a musical sound which enables us to distinguish a sharp note from a... |
vibrating body The intensity or loudness of sound I, is inversely proportional to the square of the distance from the vibrating body. ∴ Intensity α 1 (distance)2 Surface Area of the vibrating surface If the distance from the source of sound is doubled, its intensity of sound becomes 1 and so on. 4 3. Intensity is dire... |
the ears. A sound of which appears pleasant to the ear is called a musical sound whereas that which produces an unpleasant or jarring effect on the ear is called a noise. The curves shown in Fig. 8.8 (a) and (b) bring out the difference between noises and musical sounds. (a) (b) Noise Musical sound Fig. 8.8: Noise and... |
light tuning fork to one end of a string and hold the other end near the ear, by not touching it. 2. Let someone touch the spoon with a finger or the set prongs of the fork into vibration by gently hitting the prongs with a rubber. Listen to the sound produced. 3. Remember to repeat the experiment with the free end of... |
the atmosphere produce thunderstorms. These thunderstorms produce a lot of sound which we hear as thunder on the earth. Due to the spark discharge occuring between two charged clouds or between a cloud and the earth, electric spark discharge, called the lightning occurs. Though the sound due to thunder is produced fir... |
change in the temperature of a gas changes its density and hence affects the speed of sound through it. If temperature increases, the density of air decreases and hence the speed of sound increases. If temperature decreases the reverse is the effect. 233 (e) Wind Wind “drifts” air through which the sound waves travel.... |
placed in between the two tubes to prevent the sound waves from the stopwatch to reach the ear directly. Metal plate reflector A S B Stop watch Ear Fig. 8.10: Reflection of sound waves 3. Adjust the position of tube B until the sound heard is the loudest. 4. Measure angles of incidence i and reflection r. What do you ... |
a large hard surface such as the wall of a building and clap your hands. What do you hear? 2. How can you determine the speed of the sound you hear? In Activity 8.7, you will hear two sounds; the one you produce and the reflected sound. The reflected sound produced is called an echo. An echo is a reflection of sound f... |
the echo after 1.2 s. If the speed of sound in air is 330 m/s, calculate the distance between the man and the cliff. Solution Let the distance between the man and the cliff be x. (Fig. 8.12) x man cliff Fig. 8.12. Speed of sound = 330 m/s = Total distance Total time 2x 1.2 2x = 330 × 1.2 = 396 m ∴ x = 198 m The distan... |
Calculate: (a) The speed of sound in air, (b) The distance between the cliffs. 6. An echo of the sound produced by a whistle is heard after 0.50 s. If the speed of sound in air is 332 m/s, find the distance between the whistle and the reflecting surface. 8.10 Sound pollution Sound is a very important form of energy. H... |
tall wall etc. • Speed of sound in air can be determined by echo method. • Density of air, humidity, temperature and wind affect the speed of sound. • Pressure, amplitude of wave and loudness of sound do not affect the speed of sound. • Ultrasonic wave is a sound wave that have a fundamental frequency above the human ... |
heard the first echo after 3 s and the second echo 2 s later. Calculate: (a) The speed of sound in air. (b) The distance between the cliffs. 12. A worker uses a hammer to knock a pole into the ground (Fig. 8.14). hammer cliff boy worker girl Fig. 8.14: A worker knocking hammer against the pole (a) A girl at the foot o... |
and Understanding • Understand the nature of heat • and describe its effects on matter Skills • Design tests to show the factors affecting heat transfer, distinguish between conduction and radiation of heat, and between good and bad conductors of heat. • Observing carefully. • Predict expectations. • Use appropriate m... |
processes take place. 3. Describe one application of each type of the above modes of heat transfer in real life. 4. Present your findings to the rest of the class in a class discussion. There are three modes of heat transfer: conduction, convection and radiation. Conduction of heat is through solids, convection in flu... |
passed from one point to another till the other end becomes hot. Hence, in conduction, energy transfer takes place by vibration of the molecules. There is no actual movement of the heated particles. 248 To demonstrate that heat energy flows due to a temperature difference Activity 9.4 (Work in groups) Materials: • An ... |
stick bunsen burner iron Fig. 9.4: Comparing heat transfer through different conductors 3. Which rod falls first? Which one falls last? 4. Why do you think hey did not fall all of them at the same time? The matchstick falls off from the copper rod first then aluminium and finally from the iron rod. When the temperature... |
gases To investigate convection current in air Activity 9.7 (Work in groups) Materials • A box with a glass window, and two chimneys • A candle • Smouldering pieces of wick Steps 1. Take a box with a glass window and two chimneys fixed at the top. 2. Place a lighted candle under one chimney and hold a smouldering piec... |
. It is for this reason that steam is used to rotate the turbine in geothermal electric plants. 9.2.3 Heat transfer by radiation 9.2.3.1 The concept of radiation If you stand in front of a fireplace, you feel your body becoming warm. Heat energy cannot reach you by conduction as air is a poor conductor of heat. How abo... |
of heat energy radiated depends upon the temperature of the body. In Activity 9.9, if the bunsen burner is replaced by a candle flame, it will take a longer time for the wax to melt. The temperature of the candle flame is lower than that of a bunsen burner. Heat transfer can take place without contact or in a vacuum. ... |
group members how natural phenomena like sea and land breeze take place. 6. Make a presentation on your findings to the whole class through your group secretary. 1. Vacuum flask The vacuum flask popularly known as thermos flask, was originally designed by Sir James Dewar. It is designed such that heat transfer by cond... |
the sea water rises Fig. 9.15: Land breeze 4. Electrical devices An electric kettles has its heating coil at the bottom. A refrigerator has the freezing unit at the top. 5. Domestic hot water system A domestic hot water supply system works on the principle of convection current. A schematic diagram of a hot water supp... |
very high temperatures can be reached. Exercise 9.1 1. Distinguish between heat and temperature. 2. What are the different modes of heat transfer? Explain clearly their difference using suitable examples. 3. State three factors which affect heat transfer in metals. Explain how one of the factors you have chosen affect... |
due to contraction. Solids expand i.e increase in length on heating and contract i.e reduced in length on cooling. Activity 9.13 (Work in groups) To demonstrate the bending effect of expansion and contraction Materials: • A bimetallic strip Steps • Bunsen burner 1. Observe a bimetallic strip at a room temperature (Fig... |
Clamp one end of a long thin metal rod tightly to a firm support, with the end of the rod resting on a roller fitted with a thin pointer (See Fig. 9.21). clamp pointer fixed to roller thin copper rod deflection of the pointer roller table heat Fig. 9.21: Expansion and contraction of thin metal rods. 2. Heat the metal ... |
� Then, Δl = l – l0 The above expression may be expressed in terms of l0, lθ, θ and α as follows. α = Δl l Δθ = l – l0 l Δθ Re-arranging l – l = l0 αΔθ l = l0 + l0 αΔθ l = l0(1 + αΔθ) 265 Example 9.1 A copper rod of length 2 m, has its temperature changed from 15 °C to 25 °C. Find the change in length given that its co... |
molecules of a solid are closely packed and are continuously vibrating about their fixed positions. When a solid is heated, the molecules vibrate with larger amplitude about the fixed position. This makes them to collide with each other with larger forces which pushes them far apart. The distance between the molecules... |
heated or cooled to a temperature change of Δθ, its volume increases or decreases by ΔV to a new value V. The ratio of the change in volume to original volume i.e ΔV V0 to the change in temperature (Δθ). is directly proportional α Δθ ⇒ ΔV V0 ΔV V0 Hence ϒ = = ϒΔθ (ϒ is a constant called coefficient of volume expansivi... |
cm × 8 cm at 10 °C. What is the change in volume and the new volume if the temperature increases to 90 °C? 5. A solid plate of lead of linear expansion 29 × 10-6 /°C is 8 cm × 12 cm at 19 °C. What is the change in area and the new area of the lead if the temperature increases to 99 °C? 9.3.2 Thermal expansion and cont... |
liquids and solid because their molecules move furthest on heating. The following activity will help us to study expansion and contraction in gasses. Activity 9.17 To demonstrate expansion of gases (Work in pairs or in groups) Materials: • A thin glass flask • A long narrow glass tube Steps • A rubber stopper 1. Take ... |
. Electric thermostats A thermostat is a device made from a bimetallic strip that is used to maintain a steady temperature in electrical appliances such as electric iron boxes, refrigerators, electric geysers, incubators, fire alarms and the automatic flashing unit for indicator lamps of motor cars. Fig. 9.26 show two ... |
in railway tracks Gaps are left between the rails when the railway tracks are laid. The rails are joined together by fish-plates bolted to the rails. The oval shaped bolt holes allow the expansion and contraction of the rails when the temperature changes (Fig. 9.29). rail rail gap Bolts Oval shaped bolts holes fish pl... |
of breakage. Exercise 9.3 1. Use particles model to explain thermal expansion of solids. 2. Explain why: (a) Steel bridges are usually supported by rollers on one loose side. (b) Metal pipes carrying steam and hot water are fitted with loops. 3. Describe how shrink fitting is done. 4. State two applications of contrac... |
Movement of particles due to changes in density. in liquids and gases 7. Explain the following statements: (a) A metallic seat seems to be hotter during the day and colder during the night than a wooden seat under the same conditions. (b) The bottom of cooking vessels are usually blackened. (c) It is safer to hold the... |
to the north of the earth. 10.1 Definition of a magnet Activity 10.1 To identify magnets (Work in groups) Materials: Cooking stick, steel nail, a bar magnet, a spanner, a cork Steps 1. Identify a magnet from the materials provided (see Fig. 10.1). Suggest a reason why you think the material you have identified is a ma... |
agnetic materials. These include nickel, iron, cobalt and steel. Materials that are not attracted by a magnet are called non-magnetic materials. Examples of non-magnetic materials include copper, brass, aluminium, wood, cork, plastic etc. When metals are mixed together, they form alloys. Some alloys are ferromagnetic m... |
swings in a horizontal plane. 3. Note the direction in which the magnet finally comes to rest. Suggest a reason why it rests in that direction. 4. Repeat the activity at different places and note the resting direction of the magnet. What do you observe about the resting direction of the magnet? Explain the direction o... |
ises the blood that was shed for the independence of our country. Let us always live happily with one another and keep peace in our beautiful country. 10.4 Test for magnetism Basic law of magnetism Activity 10.6 (Work in groups) To establish the basic law of magnetism Materials: Two bar magnets, cotton thread. 285 Step... |
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