1. Physics Module Form 5 Chapter 4- Electronics GCKL 2010
4-1
UNDERSTANDING THE USES OF THE CATHODE RAY
O S C I L L O S C O P E ( C . R . O . )
What is
thermionic
emission? __________________________________________________________________________________
(a) Label the figure of a vacuum tube:
(b) ………… emitted are accelerated ………….. the anode by the high ……………………
between the cathode and anode.
What is cathode
rays?
A beam of electrons moving at high speed in a vacuum
Properties of Cathode Rays
1. What is the characteristics of the cathode rays?
(i) ……………………………………………………………………..
(ii) …………………………………………………………………….
(iii) ……………………………………………………………………
What it working
principle of the
cathode ray
oscilloscope ?
Structure of the Cathode Ray Oscilloscope
1. Label all parts of Cathode Ray Oscilloscope below.
4.1
Figure 9.1
.

2. Physics Module Form 5 Chapter 4- Electronics GCKL 2010
4-2
2. Fill in the blank all components and its functions.
Figure 9.3

3. Physics Module Form 5 Chapter 4- Electronics GCKL 2010
4-3
What is the
energy change?
eVchangeEnergyPotential
The principle of conservation of energy is the change of ____________ electric energy to ________
energy.
eVmv 2
2
1
,
How to measure
voltage?
How to measure
short time
intervals?
To measure a D.C voltage:
The unknown voltage, V = (Y-gain) × h
To measure a A.C voltage:
Peak-to-peak voltage, Vpp = (Y-gains) × h
Peak voltage, Vp = (Y-gains)
2
1
 (h)
Short time intervals, t = no. of divisions between two pulses × time-base value.
Examples
1. The diagram shows the trace on the screen of a CRO when an a.c voltage is connected to the
Y-input. The Y-gain control is set at 2 V/div and the time base is off.
Calculate the value of :
(a) Peak-to-peak voltage, Vpp
(b)Peak voltage, Vp.
Solution:
2. An ultrasound signal is transmitted vertically down to the sea bed. Transmitted and reflected
signals are input into an oscilloscope with a time base setting of 150 ms cm-1
. The diagram
shows the trace of the two signals on the screen of the oscilloscope. The speed of sound in
water is 1200 ms-1
. What is the depth of the sea?
Solution:
2
2
1
changeEnergyKinetic mv
Figure 9.11

4. Physics Module Form 5 Chapter 4- Electronics GCKL 2010
4-4
4.2 UNDERSTANDING SEMICONDUCTOR DIODES
What is
semiconductor?
It is …………………………………………………………………………….................................
…………………………………………............................................................................................
What is the
“doping”
process?
What is
semiconductors
diodes?
……………………………………………………………………………………………………………
…………………………………………………………………………………………………………
1. Fill in the blank for the statement below.
(a) n-type semiconductor
Silicon like Silicon doped with ………………atoms such as …………… or phosphorus. The
phosphorus atoms have …….. valence electrons. The fifth electron is free to move through
the silicon. The silicon has ….………………….. as majority charge-carriers and it thus
known as an n-type semiconductor.
(b) p-type semiconductors
Semiconductor like Silicon doped with ……………….. atoms such as ………… or indium
has more positive holes. The Boron atoms have only …………. valence electrons with
missing an electron. The majority charge-carriers in this semiconductor are the
……..................... and this semiconductor known as a p-type semiconductor.

5. Physics Module Form 5 Chapter 4- Electronics GCKL 2010
4-5
What is the
function of
diodes?
Semiconductor Diode
A diode is a component (device) that allows _______________to flow in ________ direction only.
A diode acts like a one-way valve to electric current.
The following figure shows structure and the symbol of a semiconductor diode :
Draw the symbol for a semiconductor diode.
How does the p-n junction diode work?
Any further movement of _____________ across the boundary in the depletion layer will be repelled
by the charges in the layer.
The layer of the negative charge in the p-type region will prevent the majority charge carriers from the
__________ region(the electrons) from crossing the boundary. Similarly , the positive charge layer in
the n-type region will prevent the majority charge carriers from the __________region(the holes) from
crossing the boundary in the opposite direction.