12 A semiconductor diode is made from
combination of an n-type semiconductor and p- type
semiconductor.
Diod semikonduktor diperolehi dengan
mencantumkan semikonduktor jenis–n dan semikonduktor
jenis-p.
(a) Explain how an n-type semiconductor is
produced.
Terangkan bagaimana
semikonduktor jenis-n dihasilkan.
[2 marks]
(b) Diagram 12.1 and 12.2
shows a circuit consisting of a diode and a bulb.
Rajah
12.1 dan 12.2 menunjukkan litar yang disambungkan kepada diod dan mentol.
(i) Based on Diagram 12.1 and Diagram
12.2, which bulb will
light up?
Berdasarkan
Rajah 12.1 dan Rajah 12.2, mentol yang manakah
akan menyala?
[1 mark]/[1 markah]
(ii)Explain how the bulb
will light up.
Terangkan bagaimana mentol
boleh menyala.
[3 marks]
(c)You are required to set up a
battery charger for your handphone by using
lower a.c input voltage as in
Diagram 12.3 and in Table 12.1.
Anda dikehendaki untuk menyediakan satu
pengecas bateri talifon bimbit dengan menggunakan
voltan ulang alik yang rendah dengan menggunakan maklumat seperti dalam Rajah
12.3 dan dalam Jadual 12.1.
Study the information in Diagram 12.3 and Table
12.1(a),(b)&(c) determine:
Kaji
maklumat dalam Rajah 12.3 dan Jadual 12.1(a),(b)&(c) tentukan:
(i) the
number of turns in the primary coil and the secondary coil of the transformer
and justify your choice.
bilangan lilitan dalam gegelung primer dan
bilangan lilitan dalam gegelung sekunder bagi transformer dan jelaskan pilihan
anda.
|
|
|
Ratio Np:Ns
|
|
|
100
80
60
40
20
|
Table 12.1(a)
(ii)the type of core you will use in
the transformer and justify your choice.
Jenis
teras yang anda akan gunakan bagi transformer itu dan jelaskan pilihan anda.
|
Type of
transformer core
Jenis teras transformer
|
|
Solid copper core
Teras kuprum
Laminated copper
core
Teras kuprum
berlamina
Solid
soft iron core
Teras besi lembut
Laminated soft iron
core
Teras besi lembut
berlamina
|
Table 12.1(b)
(iii) the
diode arrangement you will use and justify your choice.
susunan diod yang akan anda
gunakan dan jelaskan pilihan anda.
|
Diode arrangement
Susunan
diod
|
|
Half-wave rectification ircuit.
Litar rektifikasi
gelombang separuh.
Full-wave rectification ircuit.
Litar rektifikasi
gelombang penuh.
|
Table 12.1(c)
[6 marks]/[ 6 markah]
(d) (i) Draw
a circuit to produce full-wave
rectification and show the input voltage and the output voltage wave forms.
Lukiskan litar yang digunakan untuk
menghasilkan rektifikasi gelombang penuh dan tunjukkan bentuk gelombang bagi
voltan input dan voltan output
(ii) Explain why a capacitor is connected in
the Diagram 12.3 and how it
functions.
Terangkan
mengapa kapasitor disambungkan dalam Rajah 12.3 dan bagaimana ia berfungsi.
[8 marks]
-doped with pentavalent atom such as phosphorous
- each pentavalent atom contribute one free
electron
(i)
Bulb 12.2
(ii)
-
Electron from n-type drift to p-n junction
-
Holes from p-type drift to p-n junction
At the junction electrons and holes combines to
ensure continuous current flow. Bulb light up
(i) Ratio Np: Ns
=Vp:Vs
=240V:24V
=100 ( to get 24 V output)
(ii)type of core :Laminated soft iron core (reduce power loss
due to eddy current in the core)
(iii)full wave rectification: (less power loss &
continuous current)
Full wave rectification circuit diagram
Input signal – alternating current
v
Output signal –
full wave rectification
Why
-
To smoothen the current
How
-
When current increases in circuit capacitor stores
charges
-
When current decreases in the circuit capacitor
discharges (supply charges to the circuit)
Make the current flow more stable