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banking terms

By Victor S. Fischer
  ✍️ CRR Cash Reserve Ratio is the minimum fraction of total deposits of a bank’s customers that banks have to hold as reserves with the central bank. ✍️ SLR Statutory Liquidity Ratio is the ratio of liquid assets to the net demand and time liabilities. ✍️ LAF Liquid Adjustment Facility is a tool to allow banks to borrow money through repurchase agreements. It consists of repo and reverse repo operations. ✍️ MSF Marginal Standing Facility allows scheduled banks to borrow funds overnight from RBI against approved government securities. ✍️ MSS Market Stabilization Scheme is a monetary policy intervention by RBI to withdraw excess liquidity by selling government securities in the economy. ✍️ OMO Open Market Operations refers to the buying and selling of government securities in the open market so as to expand or contract the amount of money in the banking system. ✍️ REPO Repo...
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Basic of heating effect of electric current

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Heat energy is generated when current flows through a conductor. The heating effect of an electric current depends on below-given factors:


The resistance, R of the conductor= A higher resistance produces more heat.


The time, t for which current flows= The longer the time the larger the amount of heat produced


The amount of current, I= Higher the current, larger the amount of heat generated.


Joule’s Equation of Electrical Heating


Hence the heating effect produced by an electric current, I through a conductor of resistance, R for a time, t is given by H = I2Rt. This equation is called the Joule’s equation of electrical heating.


Electrical energy and power


The work done in pushing a charge around an electrical circuit is given by Work= VIt


So that power, P = Work /t = VI


The electrical power consumed by an electrical appliance is given by P = VI = I2R = V2/R


Numerical


An electrical bulb has 100W & 240V. Calculate - 


a)The current through the filament
b)The resistance of the filament used in the bulb.


Solution


I = P/V = 100/240 = 0.4167 A


R = P/I2 = 100/ 0.41672 = 576.04 Ω or R = V2/P =2402/100 = 576 Ω


Numerical


Find the energy released in 5 minutes by an electric bulb with a filament of resistance of 500 Ω connected to a 240 V supply.


Solution


E = Pt = V2/R *t = (2402 *5*60)/500 = 34,560 J


Numerical


A 2.5 kW immersion heater is used to heat water. Calculate:


The operating voltage of the heater if its resistance is 24Ω


The electrical energy converted to heat energy in 2 hours.


Solution


1. P=VI=I2R


I = (2500/24)1/2 =10.2062A


V=IR= 10.2062 * 24 = 244.9488V


2. E = VIt = Pt = 2500*2*60*60 = 1.8 * 107J


OR E= VIt = 244.9488 * 10.2062 * 2 * 60 * 60 = 1.8 * 107J


Numerical


An electric bulb is labeled 100W, 240V. Calculate:


The current through the filament


The resistance of the filament used in the bulb.


Solution


P = VI I = P/V = 100/240 =0.4167A
From Ohm’s law, V =IR R=V/I =240/0.4167 = 575.95Ω


Applications of the heating effect of electric current


Almost all household electrical appliances convert electrical energy into heat by heating effect.


Example- filament lamps, electric heater, electric iron, electric kettle, etc.


In lighting appliances


Filament lamps- It is made of a tungsten wire enclosed in a glass bulb from which air has been removed. This is because air would oxidize the filament. The filament is heated up to a high temperature and becomes white hot. Tungsten is used due to its high melting point; 34000 The bulb is filled with an inactive gas e.g. argon or nitrogen at low pressure which reduces evaporation of the tungsten wire. However, one disadvantage of the inert gas is that it causes convection currents which cool the filament. This problem is minimized by coiling the wire so that it occupies a smaller area which reduces heat loss through convection.


Fluorescent lamps- these lamps are more efficient compared to filament lamps and last much longer. They have mercury vapour in the glass tube which emits ultraviolet radiation when switched on. This radiation causes the powder in the tube to glow (fluoresce) i.e. emits visible light. Different powders produce different colours. Note that fluorescent lamps are expensive to install but their running cost is much less.


In electrical heating


Electric Cookers- electric cookers turn red hot and the heat energy produced is absorbed by the cooking pot through conduction.


Electric Heaters- radiant heaters turn red at about 9000C and the radiation emitted is directed into the room by polished reflectors.


Electric Kettles- the heating element is placed at the bottom of the kettle so that the liquid being heated covers it. The heat is then absorbed by water and distributed throughout the whole liquid by convection.


Electric Irons- when current flows through the heating element, the heat energy developed is conducted to the heavy metal base raising its temperature. This energy is then used to press clothes. The temperature of the electric iron can be controlled using a thermostat (a bimetallic strip).



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