Railway Science (Physics-Heat and Thermodynamics)

Immersion rod. Joule’s Law of Heating - The rate at which resistance in a circuit converts electrical energy into heat energy. The joule’s first law shows the relationship between heat produced by flowing electric current through a conductor. H = I²RT. Electromagnet is a device consisting of a core of magnetic material surrounded by a coil through which an electric current is passed to magnetize the core. The electric bell is a simple circuit that triggers a sound on the completion of the circuit by pressing the button.

3422 °C. Tungsten (or, Wolfram) has the highest melting point. Thus tungsten filament does not melt even when a large amount of heat is produced due to passage of current through the filament. It is exceptionally strong, and brittle in nature. It has the greatest high-temperature strength, and lowest thermal expansion coefficient of any metal.

Electric plugs and switches. Joule's law of heating - When an electric current is passed through a high resistance wire, like nichrome wire, the resistance wire becomes very hot and produces heat. Applications - fuse used in an electric circuit, Electric iron, Electric kettle.

Thermal power plant. Nuclear power plants produce electricity from the heat created when atoms of nuclear elements are split within a nuclear reactor. This process is called nuclear fission. Hydro electric power is a renewable source of energy that generates power by using a dam or diversion structure to alter the natural flow of a river or other body of water. Solar power plant is a facility that converts solar radiation, made up of light, heat into electricity.

Ignition temperature. The normal boiling point is the temperature at which the vapor pressure is equal to the standard sea-level atmospheric pressure. At sea level, water boils at 100° C (212° F). The average normal body temperature is generally accepted as 98.6°F (37°C).

water (H₂O). Specific Heat - It is the quantity of heat required to raise the temperature of one gram of a substance by one Celsius degree. Specific Heat of water - 4.186 joule/gram °C. Aluminum (Al), atomic number 13 - . Aluminum has a density lower than those of other common metals about one-third that of steel. Kerosine - It is also called paraffin or paraffin oil, a flammable hydrocarbon liquid commonly used as fuel.

Subtract 273 from the given temperature. Formula (For converting Kelvin to Celsius), C = K - 273. Temperature Scales: Thermometers measure temperature according to well-defined scales of measurement. The three most common temperature scales are the Fahrenheit, Celsius, and Kelvin scales. Kelvin is the SI unit of temperature. The Celsius scale has a freezing point of water at 0ºC and the boiling point of water at 100ºC. On the Fahrenheit scale, the freezing point of water is at 32ºF and the boiling point is at 212ºF.

Does not change. Latent heat of Fusion is the amount of heat energy required to change a unit mass of a substance from solid to liquid state at its melting point without changing its temperature. The SI unit of latent heat of fusion is joules per kilogram (J/kg).

H = I²Rt (Joule’s Equation) where H is heat produced, I is current flow, R is resistance and t is time. Heating effect of Current - When an electric current is passed through a conductor, it generates heat due to the hindrance caused by the conductor to the flowing current. SI Unit of Heat - joules. Applications - Electric iron, Kettle, Toaster, Heater, Electric fuse.

Electric bell : It is based on the principle of magnetic effect of current. Applications of thermal effect of electric current : Electric iron, electric toaster, electric oven, electric heater, electric bulb, electric fuse, etc.