PHYSICS JUNE 2014 PAPERS
S1 JAN 2014
For unit 2 it is worth going through some of the questions below.
Projectile motion emf AND INTERNAL RESISTANCE Electromotive Force and Internal Resistance The electromotive force (e) or e.m.f. is the energy provided by a cell or battery per coulomb of charge passing through it, it is measured in volts (V). It is equal to the potential difference across the terminals of the cell when no current is flowing. Batteries and cells have an internal resistance (r) which is measures in ohmâs (W).When electricity flows round a circuit the internal resistance of the cell itself resists the flow of current and so thermal (heat) energy is wasted in the cell itself.
We can rearrange the above equation; E=IR+Ir In this equation (V) appears which is the terminal potential difference, measured in volts (V). This is the potential difference across the terminals of the cell when current is flowing in the circuit, it is always less than the e.m.f. of the cell. Example : Q1) The p.d. across the terminals of a cell is 3.0 volts when it is not connected to a circuit and no current is flowing. When the cell is connected to a circuit and a current of 0.37 A is flowing the terminal p.d. falls to 2.8 V. What is the internal resistance of the cell? A graph of terminal p.d. against current If we plot a graph of terminal potential difference (V) against the current in the circuit (I) we get a straight line with a negative gradient.We can them rearrange the e.m.f. equation from above to match the general experesion for a straight line, y = mx +c. We can them rearrange the e.m.f. equation from above to match the general experesion for a straight line, y = mx +c. We can see from the red boxes that;
UNEMPLOYMENT UNEMPLOYMENTWho is unemployed?Who will be classified as unemployed depends on how unemployment is measured. Governmentâs measure of the number unemployed is Claimant Count. These are the people who are registered as unemployed and are receiving Job seekers allowance by the government. The problem with this measure is that it may understate and sometimes overstate unemployment figures. Under estimation takes place when some people seeking job are not accounted as unemployed because they are beyond or below a certain age and are regarded out of the workforce. Some people who were out of workforce but are returning to work, for instance a married woman now intending to work, will not be accepted as unemployed at once. A skilled worker because of non availability of job is forced to do a low paid job and is under employed will not be regarded as unemployed. Under estimation also occurs when those on training schemes are not regarded as unemployed and also when disguised unemployment is not taken into account. Over estimation takes place when people on jobs unfairly receive job seekers allowance. As a response to above mentioned problems in measuring unemployment International Labour Organization has a better definition; an unemployed is a person of working age, willing and actively seeking a job and is readily available if a job is offered but is unable to find one. Measuring Rate of Unemployment:Rate of unemployment is measured by comparing the number of unemployed with the workforce. Where workforce is the number of people employed plus the number of people unemployed who are actively seeking a job. Unemployment Rate = No. of unemployed / workforce x 100 Causes of Unemployment:Frictional Unemployment: occurs when some people who have recently been out of jobs and are unable to find another temporarily, while a vacancy exists somewhere. This is a temporary phase of unemployment which a worker faces in moving from one job to another. The friction faced in this switch over is because of occupational immobility, geographical immobility and imperfect knowledge. This type of unemployment is also known as Temporal or Search unemployment. Seasonal Unemployment: takes place when people are unemployed for short period of time because of a temporary closure of the industry they belong to due to seasonal variations. For instance agriculture and tourism industryâs functioning depend on seasons of the year. The meaning of seasonal unemployment is not only restricted to unemployment due to seasonal variations only, some industries remain on & off during a year due to other reasons as well. Workers unemployed in these industries are also referred as seasonally unemployed. Structural Unemployment: This type of unemployment takes place when an industry declines and their workers are made redundant. Industrial decline can take place due to transformation process from primary to secondary to tertiary sector. It can also take place due to loss of cost advantage or due to obsolescence of the good itself. Structural unemployment also takes place when some technology replaces workers often referred as Technological unemployment. This unemployment is relatively larger in size and can last for long. This is because of lack of job vacancies or due to occupational and geographical immobility and also due to imperfect knowledge. Industrial decline sometimes hit specific region therefore the structural unemployment in the region takes place and is referred as Regional unemployment. For instance Textile industry is mainly located in Faisalabad and its decline due to many reasons has caused unemployment in Faisalabad. Cyclical Unemployment: As the name suggests, it is the unemployment related to downturn of the business cycle. The reason of moving into a recession is demand deficiency responding to which firms will cut their output drastically and workers will be made redundant on a large scale. If lower aggregate demand maintains itself for long, unemployment period may last for long. Residual Unemployment: This is relatively a new category included where the people whose work skills have been eroded or they have become work shy because of long period of voluntary unemployment due to unemployment benefits. These people if looking for a job now will be lowest on the priority list of the employers looking for workers, which will further prolong their period of unemployment. As a consequence voluntarily unemployed initially would become involuntary now. Yes! They fight over everythingâ¦Like many other conflicts on macroeconomic issues, here also, economists differ over causes of unemployment. Keynesians believed that involuntary unemployment is possible while Monetarists or New Classical economists reject the idea of involuntary unemployment. Keynes point of view is that at certain times long periods of unemployment are possible due to demand deficiency in severe recessions. Prolonged involuntary unemployment is possible when equilibrium national income stays below full employment level because of rigidity of prices and wages in moving downward. Monetarists strongly believe in market forces and advocate that if equilibrium output deviates from full employment it will be soon restored and demand deficient unemployment will be temporary. Monetarists believe that during Great Depression most of the unemployment was Real Wage or Classical unemployment. This explains that higher real wages were the cause of unemployment. At that time real wage rate was so high that it developed an excess supply of workers in the market. This Disequilibrium unemployment took place when Trade unions pulled wage rates high above equilibrium wage rate compromising on the quantity of workers employed. This also occurred because government interfered by setting minimum wage rate above equilibrium. Apart from the above debate Monetarists coined a new term Natural or Equilibrium unemployment accepting that some people will always be seen unemployed because of frictional and structural reasons. Consequences of Unemployment: First of all the most influenced is the unemployed itself, economic hardship and loss of self esteem. If unemployment period prevails work skills may also erode. On social level increase in crime rate, suicide rate, divorce rate, addiction and even an increase in birth rate has been observed in some developing countries. The biggest problem is lost output and therefore lower standard of living, depending on the rate of unemployment. Higher dependency ratio (total population / no. of people employed) will be observed. Government tax revenues will decline because lower numbers of people are on jobs now and on the other hand expenditure on unemployment related benefits will increase. Remedies of unemployment:If cause of unemployment is demand deficiency then reviving demand is the solution. It can be done by lowering direct taxes and increased government expenditure (Keynesian solution) or by increasing money supply or waiting for automatic adjustment of macroeconomic equilibrium to full employment level ( monetarists or new classical economists solution). Supply-siders believe that causes of unemployment are actually supply barriers; therefore they offer supply side policies as a remedy. |
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