Page 199 - Physics Form 5 KSSM_Neat

A Transistor Functions as a Current Amplifier CHAPTER 5
A transistor can magnify an electric current.
In Figure 5.14, the voice of the singer can be Electronics
amplified by an amplifier system.

KEMENTERIAN PENDIDIKAN MALAYSIA

Figure 5.14
Activity 5.8

Aim: To study the use of a transistor as a current amplifier
Apparatus: Transistor circuit kit, resistors (2.2 kW, 3.9 kW, 4.7 kW, 6.8 kW, 8.2 kW),
milliammeter (0 – 1 mA), milliammeter (0 – 100 mA), 6 V power supply, 1.5 V dry
cell, cell holder and connecting wires
Instructions:
1. Arrange the circuit as shown in Figure 5.15 using a 2.2 kW resistor.
Milliammeter (0 – 100 mA)
A
2
I C
Resistor Milliammeter
(2.2 kW) (0 – 1 mA)
A
1 6 V
I
B
1.5 V

Figure 5.15
2. Record the readings of A as I and A as I in Table 5.4.
1 B 2 C
3. Replace the 2.2 kW resistor with the 3.9 kW, 4.7 kW, 6.8 kW and 8.2 kW resistors and
repeat step 2.

Results:
Table 5.4

Resistance / kΩ 2.2 3.9 4.7 6.8 8.2
I / mA
B
I / mA
c
Discussion:
1. Based on the results in Table 5.4, plot the graph of I against I .
C B
2. Determine the gradient of your graph and calculate the amplification factor of the amplifier, b.
I
b = C
I
B

LS 5.3.1 189