Comment briefly on the:
(i) voltage and current readings;
(ii) input and output voltages
The candidates were expected to connect the circuit as shown, measure and record the current (mA) and voltage (V) in Table 1 and comment briefly on both readings and the input and output voltages.
The expected answers were:
(c) Table 1
Resistance RB (Ω) |
1 kΩ |
2 kΩ |
4 kΩ |
6 kΩ |
8 kΩ |
10 kΩ |
Current (mA) |
6.273 |
3.532 |
2.058 |
1.599 |
1.366 |
1.188 |
Voltage (V) |
4.973 |
4.961 |
4.928 |
4.119 |
1.780 |
0.000 |
(i) i. current decreased with increase in resistance; voltage changed with current up to I = about 2 mA and remained fairly steady thereafter. That appears to define the Zener output.
ii. input voltage was set at 12 V(DC) and output voltage varied as described above.
Only a few candidates recorded measurement results of the type required. Majority of the candidates could not comment accurately on the voltage and current readings and the input and output readings