Page 176 - Physics Form 5 KSSM_Neat

Uses of Transformers in Daily Life
Transformers have a wide range of uses. The following are some examples of machines that use
step-down transformers and step-up transformers.

Step-down transformer Step-up transformer

• Notebook computer charger • Microwave oven
V KEMENTERIAN PENDIDIKAN MALAYSIA
• Photocopy machine • Defibrillator
• Welding machine • X-ray machine

Activity 4.18 ISS ICS

Aim: To search for information on the applications of transformers in daily life
Instructions:
1. Carry out a Hot Seat activity.
2. Gather information on the applications of transformers in daily life such as:
(a) electrical appliances
(b) electrical energy transmission and distribution systems
3. Information can be obtained from websites or by referring to your Form 3 Science Textbook.
4. Present your findings in the form of a folio.

Example 1
I I
A transformer that is connected to a 240 V P S
power supply supplies 27 W of power at a
voltage of 18 V to an electronic equipment, 18 V Electronic
as shown in Figure 4.36. Assuming the 240 V 27 W equipment
transformer is ideal:
(a) calculate the number of turns of the N P N = 60
S
primary coil. Figure 4.36
(b) calculate the current in the secondary circuit.
(c) calculate the current in the primary circuit.

Solution

(a) V = 240 V, V = 18 V, N = 60 (b) Output power = 27 W (c) V I = V I
S
S S
P P
S
P
V N V I = 27 240 × I = 18 × 1.5
S S
S = S 18 × I = 27 P
P N P S 27 I = 18 × 1.5
240
P
18 = 60 I = 18 = 0.1125 A
S
240 N P = 1.5 A
N = 240 × 60 = 800
P 18
166 LS 4.3.4