Q: What is a Leslie cube and what is it used for?
A: A Leslie cube is a hollow, watertight metal cube (often made of materials such as aluminium) used to explore the principles of thermal energy and the emission of infrared radiation. It allows investigation into how different surfaces emit infrared radiation.
Q: What types of surfaces are found on a Leslie cube?
A: A Leslie cube has four different surfaces on its vertical faces, such as matte black paint, matte white paint, shiny silver (metal), shiny black, and dull metal finishes. These varying surfaces allow comparison of how different textures and colours affect infrared emission.
Q: Why does a Leslie cube have different surface types?
A: The different surfaces allow us to investigate how the nature of a surface (its colour and texture) affects how much infrared radiation it emits or absorbs.
Q: What is the aim of the Leslie cube experiment?
A: The aim is to investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.
Q: What is infrared radiation and where is it emitted from?
A: Infrared radiation (IR) is a type of electromagnetic wave that is emitted from the surface of all objects.
Q: Do all objects emit and absorb infrared radiation?
A: Yes, all objects continually emit and absorb infrared radiation at all times.
Q: How does temperature affect the amount of infrared radiation emitted?
A: The hotter an object is, the more infrared radiation it emits in a given time.
Q: What happens when an object is hotter than its surroundings?
A: When an object is hotter than its surroundings, it emits more infrared radiation than it absorbs, causing it to cool down.
Q: What happens when an object is cooler than its surroundings?
A: When an object is cooler than its surroundings, it absorbs more infrared radiation than it emits, causing it to warm up.
Q: What happens when an object is at a constant temperature?
A: When an object is at a constant temperature, it emits infrared radiation at the same rate that it absorbs it.
Q: How do different surfaces affect infrared radiation emission and absorption?
A: Some surfaces emit and absorb infrared radiation better than others. Black surfaces are better emitters and absorbers than white surfaces, and matte surfaces are better than shiny surfaces.
Q: Why would a black radiator be more effective than a white one?
A: A black radiator would emit more infrared radiation than a white one, making it more effective at transferring heat to its surroundings.
Q: What apparatus is required for the Leslie cube experiment?
A: The apparatus includes a Leslie cube, boiling water, a heatproof or heat-resistant mat, a thermometer, and an infrared detector.
Q: Why is boiling water used in the Leslie cube experiment?
A: Boiling water is used to heat the cube so that all surfaces reach a high and consistent temperature, enabling accurate comparison of infrared radiation emitted from each surface.
Q: How should the Leslie cube be set up before taking measurements?
A: The Leslie cube should be placed on a heatproof or heat-resistant mat and filled almost to the top with boiling water, then the lid should be replaced.
Q: Why is the Leslie cube left for a short time after filling with boiling water?
A: It is left (e.g. about one minute) to allow all surfaces of the cube to heat up to the same temperature as the water.
Q: How can you check that all faces of the Leslie cube are at the same temperature?
A: A thermometer is held against each face of the cube to ensure all surfaces have reached the same temperature.
Q: How is infrared radiation measured in this experiment?
A: An infrared detector is used to measure the intensity of infrared radiation emitted from each surface, or alternatively the surface temperature can be measured.
Q: How should the infrared detector be positioned during measurements?
A: The infrared detector should be placed at a fixed distance (for example, 10 cm) from each surface when taking readings.
Q: Why must the infrared detector be kept at the same distance from each surface?
A: Keeping the detector at the same distance ensures a fair test, as distance affects the measured intensity of infrared radiation, allowing accurate comparison between surfaces.
Q: How are measurements taken for each surface of the Leslie cube?
A: The infrared detector is positioned at the same distance from one face, the radiation is recorded, and this is repeated for each of the cube’s four vertical faces.
Q: Why should the Leslie cube experiment be repeated?
A: The experiment should be repeated to ensure the results are reliable and repeatable.
Q: How should results from the Leslie cube experiment be recorded?
A: Results should be recorded in a suitable table, clearly showing the infrared radiation measured for each surface.
Q: How should the results be presented graphically?
A: A bar chart should be plotted with equal-width bars, where the x-axis represents the type of surface and the y-axis represents infrared intensity in W/m².
Q: What should be done with the results after plotting the graph?
A: The results should be used to order the surfaces from the best emitter to the worst emitter of infrared radiation.
Q: What results are typically observed in the Leslie cube experiment?
A: More infrared radiation is detected from black surfaces than white surfaces, and more from matte surfaces than shiny surfaces.
Q: Which surface is the best emitter of infrared radiation?
A: Matte black surfaces are the best emitters of infrared radiation.
Q: Which surfaces are the poorest emitters of infrared radiation?
A: Shiny white or shiny metallic surfaces are the poorest emitters of infrared radiation.
Q: What does the Leslie cube experiment demonstrate about surface properties?
A: It demonstrates that both colour (black vs white) and texture (matte vs shiny) significantly affect how much infrared radiation a surface emits.
Q: What safety hazard is present in the Leslie cube experiment?
A: The main hazard is boiling water, which can cause scalds.
Q: What control measures should be used to reduce the risk of burns?
A: Water should be poured slowly, using a funnel if necessary, the cube should not be moved while hot, and care should be taken when handling boiling water or a kettle.
Q: Why should you not move the Leslie cube when it contains boiling water?
A: Moving the cube when it is full of boiling water could cause burns or scalds if the water spills.
Q: Give an everyday example of infrared radiation causing cooling.
A: A cup of tea left on a table is hotter than its surroundings, so it emits more infrared radiation than it absorbs, causing it to cool down.
Q: Give an everyday example of infrared radiation causing warming.
A: A cold glass of water on a sunny day absorbs more infrared radiation than it emits, causing it to warm up.
Q: How can absorption of infrared radiation by different surfaces be investigated?
A: One method is to stick ball bearings to the back of different surfaces using wax and place them equal distances from a Bunsen burner, then observe which bearing falls off first as the wax melts.
Q: Why is it important to use appropriate apparatus in this experiment?
A: Appropriate apparatus ensures accurate measurement and recording of temperature or infrared radiation, leading to reliable and valid results.
Q: What type of observations should be made during the experiment?
A: Observations should focus on how electromagnetic waves (infrared radiation) affect different surfaces and how emission varies between them.
Source 1: Required Practical: Investigating Infrared Radiation: A LESLIE CUBE is a device used to explore the principles of thermal energy and emission of INFRARED RADIATION.
It’s a hollow, watertight cube typically made of metal with different surfaces on each side, such as MATTE BLACK paint, MATTE WHITE paint, SHINY SILVER, and SHINY BLACK finishes. The varying surfaces allow us to investigate how different materials and textures emit infrared radiation differently. In this practical experiment, we aim to understand how the surface material of an object affects the amount of INFRARED RADIATION it emits.
By comparing different surfaces, we can learn which materials are good emitters of infrared radiation and which are not.
Here’s how to conduct this experiment: Place a LESLIE CUBE on a heatproof mat.
Boil water and carefully fill the cube with the boiling water.
Allow the cube to warm up, then check that each side is at the same temperature with a THERMOMETER.
Position an INFRARED DETECTOR at a fixed distance from one face of the cube and record the INFRARED RADIATION it detects.
Do the same for each of the cube’s faces, keeping the detector at the same distance each time.
REPEAT the experiment to ensure reliability.
In your results, you’ll find more INFRARED RADIATION from:
the BLACK surface compared to the WHITE.
MATTE surfaces than SHINY ones.
This tells us that MATTE BLACK colors emit INFRARED RADIATION more than SHINY WHITE colors. ////////// Source 2: Investigating infrared radiation: Required practical - investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface:
There are different ways to investigate the amount of infrared radiation absorbed or radiated by a surface. It is important to:
- use appropriate apparatus to measure and record temperature accurately
- make observations regarding the effects of electromagnetic waves on different substances
The method described here uses a Leslie cube. This is a metal cube with four different types of surface. It is filled with hot water to increase its temperature.
Aim of the experiment: To investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.
Method:
Place a Leslie cube on a heat-resistant mat. Fill it, almost to the top, with boiling water and replace the lid.
Leave for one minute. This is to enable the surfaces to heat up to the temperature of the water.
Use the infrared detector to measure the intensity of infrared radiation emitted from each surface, or the temperature of the surface. Make sure that the detector is the same distance from each surface for each reading.
Results:
Record results in a suitable table. ||| Analysis:
Plot a bar chart to show the results. Make sure each bar is the same width and labelled clearly to show which surface it represents. The graph’s x-axis should be the type of surface, and the y-axis should be infrared intensity, which is measured in W/m². Use your results to order the different surfaces from the best emitter to the worst emitter of infrared radiation.
Evaluation:
Explain why the detector must be placed the same distance from each surface before taking a reading.
Hazards and control measures: Hazard: Boiling water, Consequence: Scalds, Control measures: Pour water slowly, using a funnel if necessary; do not move the Leslie cube until it has cooled. //////////// Source 3: Infrared Radiation and Temperature:
Fun Fact - although the radiators in most houses are painted white, they’d actually do their job
better if you painted them black. It’d ruin with the colour scheme in my sitting room though …
Every Object Absorbs and Emits Infrared Radiation:
1) All objects are continually emitting and absorbing infrared (IR) radiation. Infrared radiation is emitted from the surface of an object.
2) The hotter an object is, the more infrared radiation it radiates in a given time.
3) An object that’s hotter than its surroundings emits more IR radiation than it absorbs as it cools down (e.g. a cup of tea left on a table). And an object that’s cooler than its surroundings absorbs more IR radiation than it emits as it warms up (e.g. a cold glass of water on a sunny day).
4) Objects at a constant temperature emit infrared radiation at the same rate that they are absorbing it.
5) Some colours and surfaces absorb and emit radiation better than others. For example, a black surface is better at absorbing and emitting radiation than a white one, and a matt surface is better at absorbing and emitting radiation than a shiny one.
[In the example mentioned above, the hot chocolate (and the mug) is warmer than the air around it, so it gives out more IR radiation than it absorbs, which cools it down.] ||| You Can Investigate Emission With a Leslie Cube:
A Leslie cube is a hollow, watertight, metal cube made of e.g. aluminium, whose four vertical faces have different surfaces (for example, matt black paint, matt white paint, shiny metal and dull metal).
You can use them to investigate IR emission by different surfaces:
1) Place an empty Leslie cube on a heat-proof mat.
2) Boil water in a kettle and fill the Leslie cube with boiling water.
3) Wait a while for the cube to warm up, then hold a thermometer against each of the four vertical faces of the cube. You should find that all four faces are the same temperature.
4) Hold an infrared detector a set distance (e.g. 10 cm) away from one of the cube’s vertical faces, and
record the amount of IR radiation it detects.
5) Repeat this measurement for each of the cube’s vertical faces. Make sure you position the detector at the same distance from the cube each time.
6) You should find that you detect more infrared radiation from the black surface than the white one, and more from the matt surfaces than the shiny ones.
7) As always, you should do the experiment more than once to make sure your results are repeatable.
8) It’s important to be careful when you’re doing this experiment. Don’t try to move the cube when it’s full of boiling water - you might burn your hands. And be careful if you’re carrying a full kettle - your mate won’t thank you if you spill boiling water into their bag (or down their back). ||| [You can also investigate how absorption depends on surface. One way is to stick ball bearings to the back of two different surfaces with wax and see which one falls off first when the surfaces are placed equal distances from a bunsen burner.]
Q: What is a Leslie cube and what is it used for?
A: A Leslie cube is a hollow
watertight metal cube (often made of materials such as aluminium) used to explore the principles of thermal energy and the emission of infrared radiation. It allows investigation into how different surfaces emit infrared radiation.
Q: What types of surfaces are found on a Leslie cube?
A: A Leslie cube has four different surfaces on its vertical faces
such as matte black paint
Q: Why does a Leslie cube have different surface types?
A: The different surfaces allow us to investigate how the nature of a surface (its colour and texture) affects how much infrared radiation it emits or absorbs.
Q: What is the aim of the Leslie cube experiment?
A: The aim is to investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.
Q: What is infrared radiation and where is it emitted from?
A: Infrared radiation (IR) is a type of electromagnetic wave that is emitted from the surface of all objects.
Q: Do all objects emit and absorb infrared radiation?
A: Yes
all objects continually emit and absorb infrared radiation at all times.
Q: How does temperature affect the amount of infrared radiation emitted?
A: The hotter an object is
the more infrared radiation it emits in a given time.
Q: What happens when an object is hotter than its surroundings?
A: When an object is hotter than its surroundings
it emits more infrared radiation than it absorbs
Q: What happens when an object is cooler than its surroundings?
A: When an object is cooler than its surroundings
it absorbs more infrared radiation than it emits
Q: What happens when an object is at a constant temperature?
A: When an object is at a constant temperature
it emits infrared radiation at the same rate that it absorbs it.
Q: How do different surfaces affect infrared radiation emission and absorption?
A: Some surfaces emit and absorb infrared radiation better than others. Black surfaces are better emitters and absorbers than white surfaces
and matte surfaces are better than shiny surfaces.
Q: Why would a black radiator be more effective than a white one?
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Energy Stores and Transfers, Open and Closed Systems36
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Examples of Energy Transfers, Energy Flow Diagrams13
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Calculation of Energy Changes, Conservation of Energy11
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Energy Dissipation, Reducing Unwated Energy Transfers in the Home13
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Conduction and Convection112
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Specific Heat Capacity, Intro to Thermal Conductivity22
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Required Practical: Specific Heat Capacity20
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Power124
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Required Practical: Investigating Insulation121
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Efficiency108
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Types of Energy Resources290
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Trends and Uses of Energy Resources, Energy for Transport and Heating246
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Charge and Current82
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Current, Potential Difference & Resistance58
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Required Practical: Investigating Resistance89
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Resistors and I-V Graphs132
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Required Practical: I-V Graphs99
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Series and Parallel Circuits55
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Direct and Alternating Current31
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Mains Electricity78
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Electrical Power25
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Electrical Energy Transfers and Power Ratings71
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The National Grid84
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Static Electricity and Sparks77
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Electric Fields and Sparks75
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Density - Intro13
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Required Practical: Density17
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States of Matter36
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Internal Energy35
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Specific Latent Heat, Heating & Cooling Graphs (and recap of Internal Energy)36
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Particle Motion in Gases, Gas Pressure & Temp, Boyle's Law, Work Done on Gases41
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Atomic Structure, Radioactive Decay, Types of Radiation, Intro to G-M Tube75
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Nuclear Equations, Half Life, Contamination, Irradiation, Peer Reviewing79
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Background Radiation, Correct Count-Rate, Uses and Risks of Radiation45
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Nuclear Fission and Fusion97
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Scalars and Vectors24
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Contact and Non-Contact Forces71
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Gravity, Weight & Centre of Mass97
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Resultant Forces, Scale Drawings, & Components of a Force113
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Work Done and Its Energy Transfers53
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Forces and Elasticity112
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Required Practical: Force and Extension118
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Moments, Levers and Gears101
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Pressure in Fluids118
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Upthrust and Atmospheric Pressure67
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Distance and Displacement17
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Speed and Velocity25
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Distance-Time Graphs24
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Acceleration106
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Velocity-Time Graphs61
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Terminal Velocity121
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Newton's First Law and Inertia61
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Newton's Second Law and Inertial Mass51
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Newton's Third Law73
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Required Practical: Force, Mass and Acceleration137
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Stopping Distance and How Braking Works131
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Momentum and Changes in Momentum104
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Vehicle Safety Features40
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Transverse & Longitudinal Waves36
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Wave Period & Speed, Measuring the Speed of Sound in Air23
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Required Practical: Measuring Waves in a Ripple Tank19
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Required Practical: Measuring Waves on a String9
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Sound Waves and Human Hearing101
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Using Ultrasound for Imaging and Detection70
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Using Seismic Waves for Exploration81
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Intro to Electromagnetic Waves, Intro to Visible Light92
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Uses of Radio Waves91
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Uses of Microwaves25
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Uses of Infrared Radiation33
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Uses of Visible Light21
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Uses of Ultraviolet Radiation25
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Uses of X-Rays and Gamma Rays27
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Dangers of Electromagnetic Waves63
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Visible Light and Colour Filters137
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Required Practical: Investigating Infrared Radiation75
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Reflection and Refraction114
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Specular and Diffuse Reflection61
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Required Practical: Reflection and Refraction119
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Lenses and Ray Diagrams153
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Black Body Radiation and Earth’s Temperature169
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Magnetism and Types of Magnets28
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Magnetic Fields30
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Electromagnetism, The Right Hand Grip Rule and Solenoids40
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The Motor Effect55
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Fleming's Left Hand Rule41
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Electric Motors and Loudspeakers25
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Induced Potential, The Generator Effect and Microphones52
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Transformers and their Equations137
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Our Solar System and Orbital Motion184
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The Life Cycle of Stars100
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Red Shift and The Big Bang81
