heat energy and sources of energy
class 8 complete lecture.
Answers
Explanation:
Most of us refer the word ‘heat’ to anything that feels warm but scientifically, heat is defined as the flow of energy from a warm to a cooler object. The classification of heat is done on this basis as hot and cold.
Heat energy is all around us such as in icebergs, volcanoes, and our bodies. Every matter has heat energy.
Sources of Energy : Complete Set Question
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This set of questions contains all the possible concepts
which could be asked in the examination
Sources of Energy
INTRODUCTION
Q.1 What is energy crisis?
An energy crisis occurs when we all have a great need of fuel or electricity but does not have enough amounts of them. For example, a large portion of the energy we use is derived from oil. Some experts claim that we will run out of oil in just a few decades
Q.2 Why energy crisis occurs?
When we use energy in its usable form like in cooking, we convert the form of energy and get our work done during the process. Since we cannot reverse the change involved in this process so we cannot get back the original usable form of energy. Due to this, it becomes important to think about energy shortage and the related energy crisis.
Q.3 List the characteristics of good sources of energy?
Or
What are the qualities of an ideal source of energy?
• It should give large amount of energy per unit mass.
• It should be easy to access.
• It should be easy to store and transport.
• It should be cheap
Q.4 What is a good source of energy?
A good source of energy is the one with following properties:
• It should give large amount of energy per unit mass.
• It should be easy to access.
• It should be easy to store and transport.
• It should be cheap
Q.5 What is a good fuel?
A good fuel is the one with following properties:
• Good fuel should give more heat.
• Should release less smoke.
• Should be cheap.
• Should be easily available.
• Safe
• Should be easy to store.
• Less ash should be left.
• Should have proper burning temperature.
Q.6 The use of dry wood as domestic fuel is not considered as good. State two reasons for it?
The two reasons for dry wood not being a good option for domestic use are:
• It gives very small amount of energy
• It produces lots of smoke.
Q.7 State three criteria for considering charcoal a better fuel than wood for domestic purposes?
The three essential properties for charcoal being a better fuel than wood for domestic use:
• No flame when charcoal is burnt.
• Charcoal produces more energy.
• Charcoal releases less smoke.
Q.8 What do you mean by renewable energy?
Renewable sources of energy are the source which can last for a very long time. It’s supply is unlimited. They are also called non - exhaustible sources of energy. Examples of such type of energy resources are sun, wind, wood and wave etc.
Q.9 What do you mean by non-renewable energy?
Non-renewable sources of energy are sources whose supply is limited and is likely to be finished one day. They are also called exhaustible sources of energy. Examples of such type of energy resources are coal, petrol etc.
Q.10 List two uses of energy in our daily life?
Two uses of energy in daily life is:
• Cooking
• Running Automobiles
SOURCES OF ENERGY
Q.11 Name three conventional sources of energy?
• Fuel
• Wind
• Bio-mass
Q.12 List two non conventional sources of energy?
• Solar energy
• Nuclear energy
Q.13 State the reason for calling fossil fuels as non-renewable source of energy?
Fossil fuel are called non-renewable source of energy as they are limited and will be over within few decades.
Q.14 Name the major constituent in natural gas?
Methane
Q.15 What are the causes of acid rain?
Due to air pollution, oxides of sulphur and nitrogen are present in air. When it rains, these oxides react with rain water to form acids. This acid falls on earth surface along with rain. This is the cause of acid rain.
Q.16 Write the characteristics features of the micro-organisms which help in the production of biogas plant?
These micro-organisms do anaerobic decomposition of slurry to form methane and other components of bio gas.
Q.17 Name two combustible components of bio-gas?
• Methane
• Hydrogen
Q.18 The chief constituent of biogas is methane. List any two other constituents of bio-gas?
• Carbon Dioxide
• Hydrogen
Q.19 Why is a biogas plant a safe and efficient method of waste disposal? Justify.
Biogas plant is a safe method of waste disposal as the waste will no longer create any pollution. Also the remains of this waste material after use in biogas plant can be used as manure.
Biogas plant is an efficient method of waste disposal as now it will be used to produce bio-gas which is a good source of energy. Also the remains of this waste material after use in biogas plant can be used as manure.