Although hydrogen has a very high calorific value, it is not used as an industrial fuel. Yes, the calorific value of hydrogen in 150kJ/g which is the highest among the gaseous fuels, but it is not used as a domestic fuel because: (I) It burns with an explosion in air. (ii) Its ignition temperature is […]
What is a balanced diet? How does the balanced diet depend on special needs? Explain with the help of two examples. Why are roughage and water important parts of a balanced diet? Name two sources of roughage in our diet.
Balanced diet: a diet (food) which contains the required amount of food nutrients such as carbohydrates, proteins, vitamins, fats, minerals, water and roughage, is known as a balanced diet. A balanced diet depends on special needs as the requisite amount of nutrients differ according to the age, sex and the kind of work of a […]
How is energy liberated in the sun? What would happen when all the hydrogen in the sun gets consumed?
The source of energy of the sun is nuclear fusion reactions in its interior, of hydrogen gas into helium nuclei. 21H + 21H —–> 42 He + Energy (i) Red giant phase: When all of the hydrogen gas in the interior of the sun is utilized, then the nuclear fusion reaction will stop […]
Q. With the help of a labeled diagram and necessary chemical equations describe the preparation of methane in the laboratory. Ans. In the laboratory, methane is prepared by heating a mixture of sodium acetate and soda lime. Soda lime is a mixture of sodium hydroxide and calcium oxide. A mixture of sodium acetate and soda […]
An electric meter shows the consumption of one unit of electric energy, for heating 20kg of water. What would be the rise in temperature of water if the entire electrical energy is used only to heat the water and there are no energy losses. Specific heat of water = 4200 J/kg/oC. Mass of the water […]
What causes the wind to blow? Explain the principle of working of a wind mill. State two advantages of using wind energy. The earth’s atmosphere acts like a giant heat engine. The sun rays are much stronger near the equator than in the polar regions. As a result, the air in the equatorial regions becomes […]
Q. A water pump can lift 500kg of water to a tank situated at the height of 10m in 10 seconds. Calculate the power of the pump (g = 10 m/s2). Ans. Mass of the water lifted = 500kg Acceleration due to gravity (g) = 10m/s2 Height up to which water is lifted = 10m […]
HOW THERMOCOUPLES MATERIALS ARE PREPARED – THERMOCOUPLING Thermocouples can be formed by joining two dissimilar materials so as to form two separate junctions. By making this combination it is seen that a thermo-emf is induced at the junction when the junctions are maintained at different temperatures. And this causes a current to flow round the […]
WHAT IS FLIGHT DATA RECORDING ? NECESSITIES OF FLIGHT DATA RECORDING There are many cases in past when due to some unfortunate reasons aircrafts were crashed and lives of many people were lost. It is therefore, necessary that whatever the reasons of the crashes of the aircrafts they must not be allowed to repeat in […]
We all are aware that depending on the type of systems, and the extent to which electrical power is to be utilized for their operation, the primary of such power may either be direct current or alternating current. And generators are those devices which provide electrical power to those components depending on their requirement. The […]
VARIATIONS IN PROPERTIES OF MATERIALS WITH TEMPERATURE Variation of some property of a substance with temperature is utilized in most forms of temperature measurement. Here, today, we will discuss about some of the properties which alter in various substances with temperature. You would have come across many substances which expand as their temperature rises. So, […]
HOW IS LEVELING AND COMPENSATION ACHIEVED IN AIRCRAFT Before a free gyroscope is utilized in an aircraft as an attitude sensing element, it must be tied to the earth by gravity sensing. Therefore it is necessary to provide systems which will level erecting gyroscopes to their appropriate reference datum and compensate for any tendency to […]