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Grade thresholds

PHYSICS GCE Advanced Level and GCE Advanced Subsidiary Level Grade thresholds taken for Syllabus 9702 (Physics) in the May/June 2011 examination. The thresholds (minimum marks) for Grades C and D are normally set by dividing the mark range between the B and the E thresholds into three. For example, if the difference between the B and the E threshold is 24 marks, the C threshold is set 8 marks below the B threshold and the D threshold is set another 8 marks down. If dividing the interval by three results in a fraction of a mark, then the threshold is normally rounded down. Grade A* does not exist at the level of an individual component. The thresholds for the syllabus are determined first by adding together the thresholds for the components taken by the candidate. A reduction may be made at the higher grades depending on the correlation of the papers. If the maximum raw marks for the components are not in the weighting/relationship specified in the syllabus, a weighting is applied...
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Alternating Current

Alternating Currents Characteristics of alternating currents Peak current, I 0  = 3 A Peak-to-peak current, I p-p  = 6 A Period, T  = 20 ms Frequency, f = 1 / T  = 50 Hz Angular Frequency, ω = 2 π f = 314 rad s -1 Instantaneous current: the current at a particular instant. Since this A.C. signal can be described by the equation: I = I0 sin (ω t) or V = V0 sin (ω t) the instantaneous current I or voltage V at time t is given by  I 0  sin (ωt)  or  V 0  sin (ωt) . Note:  Both the period and amplitude of a sinusoidal A.C should be  constant . Root-mean-square current of an alternating current  is defined as that  steady {NOT  direct }  current that produces the  same heating effect  {ie I 2  R} as the alternating current  in a given resistor . (Instantaneous) sinusoidal current: I = I 0 sinωt  , { Similarly, V = V 0  sinωt } I rms  = I o  / √2,...
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