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Concept of Heat Heat may be defined as energy in transit. Word heat is used only if there is a transfer of energy from one thermodynamic system to the another. When two systems at different temperatures are kept in contect with each other then after some time temperatures of both the syatems become equal and this phenomenon can be described by saying that energy has flown from one system to another. This flow of energy from one system to another on account of temperature difference is called heat transfer. Flow of heat is a non-mechanical mode of energy transfer. Heat flow depends not only on initial and find states but also on path it's. Calorimetery Calorimetery means measurement of Heat. Calorimeter is the device used to measure heat and it is cylinderical vessel made of copper and provided by a stirrer and a lid. This vessel is kept in a wooden block to isolate it thermally from suroundings.A theromometer is used to measure the temperature of th

Motion with constant acceleration Motion with constant acceleration or uniformly accelerated motion is that in which velocity changes at the same rate troughout motion. When the acceleration of the moving object is constant its average acceleration and instantaneous acceleration are equal. Thus from eq. 5 we have Let v 0 be the velocity at initial time t=0 and v be the velocity of object at some other instant of time say at t 2 =t then above eq. 7 becomes or , v=v 0 +at                          (8) Graphically this relation is represented in figure 8 given below. Thus from the graph it can be seen clearly that velocity v at time t is equal to the velocity v 0 at time t=0 plus the change in velocity (at). In the same way average velocity can be written as where x 0 is the position of object at time t=0 and v avg is the averag velocity between time t=0 to time t.The above equation then gives x=x 0 +v avg t                     (9) but for the interval t=0 to

  Circuit Diagrams We already know that electric circuit is a continuous path consisting of cell (or a battery), a plug key, electrical component(s), and connecting wires. Electric circuits can be represented conveniently through a circuit diagram . A diagram which indicates how different components in a circuit have to be connected by using symbols for different electric components is called a circuit diagram. Table given below shows symbols used to represent some of the most commonly used electrical components Ohm's Law Ohm's law is the relation between the potential difference applied to the ends of the conductor and current flowing through the conductor. This law was expressed by George Simon Ohm in 1826. Statement of Ohm's Law If the physical state of the conductor (Temperature and mechanical strain etc.) remains unchanged, then current flowing through a conductor is always directly proportional to the potential difference across the two ends o

 Electric resistance of a conductor (or a wire) depends on the following factors Length of the conductor: - Resistance of a conductor is directly proportional to its length. So, when length of the wire is doubled, its resistance also gets doubled; and if length of the wire is halved its resistance also gets halved. Thus a long wire has more resistance then a short wire. Area of cross-section:- Resistance of a conductor is inversely proportional to its area of cross-section. So, when the area of cross-section of a wire is doubled, its resistance gets halved; and if the area of cross-section of wire is halved then its resistance will get doubled. Thus a thick wire has less resistance and a thin wire has more resistance. 3. Nature of material of conductor:- Electrical resistance of a conductor also depends on the nature of the material of which it is made. For example a copper wire has less resistance then a nichrome wire of same length and area of cross-section. 4

When electric current passes through a high resistance wire, the wire becomes and produces heat. This is called heating effect of current. This phenomenon occurs because electrical energy is gets transformed into heat energy when current flows through a wire of some resistance say R Ω. Role of resistance in electrical circuits is similar to the role of friction in mechanics. To we will now derive the expression of heat produced when electric current flows through a wire. To we will now derive the expression of heat produced when electric current flows through a wire. For this consider a current I flowing through a resistor of resistance R. Let V be the potential difference across it as shown in the figure 6 Let t be the time during which charge Q flows. Now when charge Q moves against the potential difference V , then the amount of work is given by Therefore the source must supply energy equal to VQ in time t. Hence power input to the circuit by the source is The energy

See Mars in the Night Sky! Simply go outside and look up, contact your local planetarium, or look for a star party near you. In 2016, the planet Mars will appear brightest from May 18 to June 3. Mars Close Approach is May 30, 2016. That is the point in Mars' orbit when it comes closest to Earth. Mars will be at a distance of 46.8 million miles (75.3 million kilometers). Mars reaches its highest point around midnight -- about 35 degrees above the southern horizon, or one third of the distance between the horizon and overhead. Mars will be visible for much of the night. By mid-June, Mars will become fainter as Mars and Earth travel farther away from each other in their orbits around the Sun. Miss seeing Mars Close Approach in 2016? The next Mars Close Approach is July 31, 2018.     What is Mars Close Approach? Close approach is when Mars and Earth come nearest to each other in their orbits around the sun. Close is a relative term. The minimum distance from the