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 Electronics Paper 1, May/June 2008
 Questions: 1 2 Main
Weakness/Remedies
Strength

Question 2

1. Connect the circuit as shown in Figure 1 using the silicon diodes DI, O2, 03,04­
2. Ask the supervisor to check the circuit connection.

Table 2

 Forward Polarity L₁ L₂ L₃ S₂ (Open) S₂ (Closed) Reverse Polarity L₁ L₂ L₃ S₂ (Open) S₂ (Closed)

(d) Close switch Si and open switch S₂
(e) Record the state of the lamps in Table 2.
(f) Close switch S₂ and record the state of the lamps.
(g) Open switch S₁ and reverse the polarity of the power supply.
(h) Repeat steps (d) to (f).
(i) Comment on the results in each case based on the action of the lamps, diodes and switches.

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OBSERVATION

Table 2 (V = 12v to Earth) for Forward Polarity.

 Position Of Switch S₂ Status Of L₁ Status Of L₂ Status Of L₃ Open ON OFF ON Closed ON OFF ON

Table 2 (V = 12v to Earth) for Reverse Polarity.

 Position Of Switch S₂ Status Of L₁ Status Of L₂ Status Of L₃ Open OFF OFF OFF Closed ON OFF OFF

In experiment 2, which was an adaptive form of experiment 1, the state of the lamp particularly in lamp 3(L₃) was got correctly by many candidates but they failed to give the comments on the results as required in 2(i).
While a few candidates who got the states of the lamps correctly had their comments inconclusively done. It was expected that their answers would include the state o the bias of the diode.