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Showing posts from July, 2020

Waves

Waves Waves transfer energy from one point to another without transferring any matter. In this chapter you will learn: Types of Waves Properties of waves Reflection of waves Refraction of waves Sound waves Seismic waves Electromagnetic waves Radio waves Uses and dangers of EM waves Types of lenses Visible light Black body radiation Perfect black bodies and radiation Types of Waves These are two types of waves: transverse and longitudinal waves . In transverse waves , the vibrations are perpendicular to the direction of energy transfer. In longitudinal waves , the vibrations are parallel to the direction of energy transfer. Properties of waves The amplitude of a wave is the

Forces

In this chapter you will learn: Scalar and vector quantities What are Contact and non-contact forces ? Weight , mass and gravity Resultant forces and work done Forces and elasticity Moments , levers and gears Pressure in fluids What is upthrust ? Atmospheric pressure Distance and displacement Speed , velocity and acceleration What is terminal velocity ? What are Newton's Law's of motion? Forces and braking What is momentum ? Scalar and vector quantities Scalar quantities Scalar quantities only have magnitude, but no specific direction. Scalar quantities examples: distance, mass, speed, time, temperature, etc. Vector quantities Vector quantities have both magnitude and spec

Atomic structure

Atomic structure In this chapter you will learn: Developing the model of the atom What are Atoms , isotopes and ions ? Atoms and nuclear radiation Half life Irradiation and Contamination Uses and risk of radiation Nuclear fission and fusion Developing the model of the atom In 1804, John Dalton proposed his atomic theory that all matter was made up of tiny hard particles or spheres called atoms that could not be broken up. In 1897, J J Thomson proposed that the atom looked like a plum pudding. J J Thomson discovered that atoms contained even smaller negatively charged particle called electrons which could be removed from atoms. He said that the atoms were spheres of positive charge with a lot of negative electrons stuck in it like fruit in a puddin

Particle model of matter

Particle model of matter In this chapter you will learn: What is Particle model of matter ? What is density, and how to calculate it? What is internal energy ? Temperature changes in a system What is specific heat capacity ? What is change of state ? What is specific latent heat ? Particle motion in gases Pressure , temperature and volume What is particle model? All matter is made up of tiny particles called atoms and molecules. Density of an object depends on the material and how its particles are arranged . Density describes the number of particles and how tightly packed they are in a solid , liquid or gas . Density in Solids, liquids and gases In a dense material the particles are packed tightly together. Whereas, in a less dense material particles are more spread out . The de

Energy resources

In this chapter you will learn: Energy resources Renewable energy resources Non-renewable energy resources Uses of energy resources Energy resources We can classify energy resources as renewable and non-renewable . Renewable energy resources Renewable energy comes from natural sources or processes that are constantly replenished. Something that can't run out. These are solar, wind, hydro-electricity, tides, bio-fuels, geothermal and water waves. Biofuels are fuels made from plants and animal wastes. They can be solid, liquid or gas. Biofuels are said to be carbon neutral, that means the amount of carbon dioxide that is absorbed by the plants is equal to the carbon dioxide that is released when the fuel is burned. Biofuels are fairly reliable, as crops can be grown in a relatively short time and different crops can be grown throughout the year. Solar cells are best sou

Electric Current and Circuits

Electric circuits In this chapter you will learn: What is an electric circuit ? What are electric charge and current ? What are Potential difference and resistance ? Different types of components . What are Series and Parallel circuits? Mains electricity What is National Grid ? What are Transformers and their types? Electrical charge and current Charge is a fundamental property of particles. There are two types of charges: positive and negative . A particle with charge experiences a force in an electric field. Electric charge is measured in coulombs , C. Current Electrical current is a flow of electrons (charge) in an electric circuit. The unit of electric current is ampere . An ammeter is used to measure the current in a circuit. A switch is used to turn a circuit on or off. As per the definition above w

Static electricity

Electrical charges All matter is made up of atoms . Atoms consist three types of particles: protons , neutrons and electrons . There are two types of electric charges: positive and negative . Electrons have negative charge . Protons have positive charge . In this chapter you will learn: What are electric charges ? What is static electricity ? What is electric field ? What are field lines ? Generally, the atom has equal number of electrons and protons; therefore, it has neutral charge. H owever, if there is a loss of electrons, the atom becomes positively charged. On the other hand, if there is a gain of electrons in the atom, it becomes negatively charged. Charged atoms are called ions . Static electricity Static electricity is the result of an imbalance between negative and positive charges in an object. Static electricity is all about electric char

Energy and heating

Energy and heating Heat energy can be transferred by conduction, convection or radiation.. Conduction Conduction is the process where vibrating particles collide with their neighbouring particles to transfer energy. Convection Convection is the process where heated particles of liquids and gases move from hotter region to cooler region. Insulation Insulation is a material that prevent heat transfer from one area to another. Thermal conductivity Thermal conductivity is a measure of the ability of a certain material to transfer energy when it is heated. Metals are very good heat conductors and transfer energy very quickly. Brick, wood and concrete are poor heat conductors. Specific heat capacity The Specific heat capacity is the amount of energy required to raise the temperature of 1 kg of a substance by 1 degree Celsius. Specific heat capacity is measured in joules per kilogram per degree Celsius (J/kg°C). Different materials need different amounts of energy

Work, power and efficiency

Work, power and efficiency In this chapter you will learn: Work, power and efficiency What is wasted energy? How to reduce unwanted transfer of energy? Work When a force acts on an object and causes it to move through a distance, then work is being done on the object by the force. When work is done, energy is transferred from one energy store to another. work done = Energy transferred work done = force × distance The units used in the equation above are as follows: Work done (energy transferred) is measured in joules, J force is measured in newtons, N Distance is measured in metres, m Worked example: Question 1 A horizontal force of 30 N causes an object to move a horizontal distance of 20 m. How much work is done on the object by the force? Answer: work done = force × distance wor

Cell Division

In this chapter you will learn: What is Cell division ? Chromosomes and DNA Mitosis and the cell cycle Stem cells Cell differentiation Cloning in plants Using human stem cells Therapeutic cloning Risks and concerns Cell division Cell division is a basic process by which a parent cell is divided into two daughter cells. This involves separation of the genetic material into two or more daughter cells. Chromosomes and DNA Chromosomes carry genetic information in a molecule called DNA . Human body cell has 23 pairs of chromosomes. DNA is the molecule that carries the genetic information . DNA is found in the nucleus of a cell. Each section of DNA that codes for a specific protein is called a gene . The majority of cells in your body have a nuc

Cell structures

In this chapter you will learn: What are Cells ? Cell structures and their functions Plant cell structures and their functions Similarities & differences between animal and plant cells Cell Specialisation - Animal Similarities & differences between animal and plant cells What are Cells? Living things are made of cells . Cells are very small. Cells can be seen through a microscope . Cells were first discovered by Robert hooke in 1665. Animal and plants are made up of lots of cells. Mostly plant and animal cells are 0.01 – 0.10 mm in size . Each cell in human body have 23 pairs of chromosomes . Bacteria are made of single cells. Cells have many types of shapes. Group of cells make a tissue . Cells play a different types of role in our body. Cells need things like glucose and oxy