Question 5:
Figure 3 shows an electronic circuit used to study the function of a npn transistor in the circuit. Readings IB and IC are obtained from microammeter, A1 and miliameter A2 respectively. The rheostat is adjusted to obtain different values of IB and IC as shown in Table 2.
(a) Plot the graph of IC against IB.
(b) Based on your graph in 5(a):
(i) state the relationship between IB and IC and explain your answer
(ii) state the roles of the transistor in the circuit and explain your answer
(c) draw a new electronic circuit if the npn transistor is replaced with a pnp transistor.
Answer:
(a)
(b)(i)
IC is directly proportional to IB. The graph of IC against IB shows a straight line passing through the origin with a positive gradient.
(b)(ii)
– Transistors play a role as current amplifiers.
(c)
Figure 3 shows an electronic circuit used to study the function of a npn transistor in the circuit. Readings IB and IC are obtained from microammeter, A1 and miliameter A2 respectively. The rheostat is adjusted to obtain different values of IB and IC as shown in Table 2.
(a) Plot the graph of IC against IB.
(b) Based on your graph in 5(a):
(i) state the relationship between IB and IC and explain your answer
(ii) state the roles of the transistor in the circuit and explain your answer
(c) draw a new electronic circuit if the npn transistor is replaced with a pnp transistor.
Answer:
(a)
(b)(i)
IC is directly proportional to IB. The graph of IC against IB shows a straight line passing through the origin with a positive gradient.
(b)(ii)
– Transistors play a role as current amplifiers.
– The graph has a positive gradient and is a straight line, so the collector current changes proportionally with the base current.
(c)
Question 6:
Amar carried out an electronic project to create an automatic switch circuit for a fire alarm system. Figure 4 shows an incomplete electronic circuit. Table 3 shows the symbols of nine possible components which may be used to complete the circuit.
(a) Based on your knowledge of electronics, select any suitable components from Table 3 to complete the transistor circuit as an automatic switch for a fire alarm system.
(b) State the justification for each of your choice.
Answer:
(a)
(b)
Amar carried out an electronic project to create an automatic switch circuit for a fire alarm system. Figure 4 shows an incomplete electronic circuit. Table 3 shows the symbols of nine possible components which may be used to complete the circuit.
(a) Based on your knowledge of electronics, select any suitable components from Table 3 to complete the transistor circuit as an automatic switch for a fire alarm system.
(b) State the justification for each of your choice.
Answer:
(a)
(b)