Page 2 - Spotlight A+ Physics Form 4.5

Extra Features of This Book

CHAPTER
7 Quantum Physics
SMART SCOPE • Explain the initiation of the quantum theory. Page 472 CONCEPT MAP
Important Learning Standard
7.1 Quantum Theory Of • Describe quantization of energy. 476 477
• Explain wave-particle duality.
Light
• Explain concept of photon. 478
Contains learning objectives • Solve problems using photon energy, E = hf and power, P = nhf. 478 479 Contents of the whole topic
• Explain photoelectric effect.
7.2 Photoelectric Effect • Identify four characteristics of photoelectric effect that cannot be 482
explained using classsical theory.
that need to be achieved in • State minimum energy required for a photoelectron to be emitted are summarised in the form
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from a metal surface using Einstein’s equation, hf = W + 1 —mv 2 max 483
2
each topic. • Explain threshold frequency, f 0 and work function, W. 485 of a concept map.
7.3 Einstein's • Determine work function of metal, W = hf 0 = hc —– λ 0 485
Photoelectric Theory
• Solve problems using Einstein’s equation for photoelectric effect. 486
Form • Explain production of photoelectric current in a photocell circuit. 488
4 Physics Chapter 2 Force and Motion I • Describe applications of photoelectric effect in daily life. 489
1. It is more difficult to move or to stop a heavier (c) The inertia of the passengers in the bus
object such as a bowling ball compared to a keep them in their initial state of rest or
lighter object such as a football. motion.
2. In Experiment 2.2 the horizontal oscillations of • Continuous energy / Tenaga selanjar
• Black body radiation / Sinaran jasad hitam
the load an inertial balance are not influenced
by gravity. • Ideal absorber / Penyerap unggul • Photoelectric effect / Kesan fotoelektrik 266
• Radiation intensity / Keamatan sinaran
3. The period of the horizontal oscillations of the • Threshold frequency / Frekuensi ambang
• Work function / Fungsi kerja
• Wave-particle duality / Kedualan gelombang-zarah
load depends on the mass of plasticine only. • The passengers fall backwards when a Pressure
• Discrete energy / Tenaga diskrit
4. The inertia of an object has a direct relationship stationary bus suddenly moves forward.
with its mass, whereby the inertia of the object
CHAP increases when its mass increases. Important Formula and Tips
2 Pressure in Atmospheric Gas Pressure Pascal’s Principle Archimedes’ Principle Bernoulli’s Principle
• Einstein’s photoelectric equation, • Photon power, P = nhf Liquids Pressure
hf = W + 1 — 2 mv 2 max in which n is the number of photons emitted per
second
Video of inertial balance • The passengers are thrown forward when a Formula, Venturi
–—
http://bit.ly/36NykFm • Work done, W = hf 0 = hc moving the bus suddenly stops. • de Broglie's wavelength, λ = h — P Formula, Applications: Manometer F 1 tube

λ 0
whereby, f 0 is threshold frequency of metal and λ 0 • Momentum of particle, p = ABBBB P = hρg • Water tank —— = F 2 —— A 2
Figure 2.43
2mK
(d) An oil tanker lorry has large inertia. Thus,
is the threshold wavelength of metal whereby, K = 1 — 2 mv 2 • Intravenous liquid Water Buoyant Formula,
A 1
The Effects of Inertia in Daily Life • Photon energy, E = hf = hc the storage tank is divided into three • Dam manometer force, F F = ρVg Aerofoil
–—
sep
λarate compartments to reduce the
1. The astronauts in the International Space impact of the inertia of petrol on the walls • Siphon Applications:
Mercury
Station (ISS) are in zero gravity contition, hence of the tank when the lorry stops abruptly. Factors manometer • Piston’s Pascal
470
they need the inertial balance to measure mass. • Depth in • Hydraulic system Weight of object in Lift force
(Hydraulic jack,
floating state, W
2. Examples of inertia situation in daily life and
liquid
SPOTLIGHT PORTAL its effects: • Density of Angle of
hydraulic brake)
(a) The rain drops are in motion as when the
liquid
umbrella rotates. When it stops rotating,
the inertia of the rain drops causes the
Figure 2.44
rain drops to continue in motion and leave (e) When a roller coaster changes direction Measuring instruments: Units of pressure W = F W . F W , F attack
the surface of the umbrella. suddenly, the inertia of the passengers • Mercury barometer • Pascal, Pa Floating at Moving Moving Applications:
keeps them to maintain their original • Fortin barometer • mm Hg a stationary downwards with upwards with • Bunsen burner
• Aneroid barometer
• m H 2 O
• Racing car
Scan QR code to visit state of motion. The passengers must wear • millibar position an acceleration an acceleration • Sports
safety belts to remain in their seats and not
• Aeronautics
thrown out of the carriage when it moves
at sudden changes of speed and direction. Effects of atmospheric pressure • Ship and Plimsoll line
Applications
websites or videos related Photograph 2.2 • at high altitude • Submarine
• at extreme depth
• Hot air balloon
(b) The chilli or tomato sauce can be poured
out from the glass bottle by jerking the
to subtopics learnt. There bottle downwards and stopping it abruptly.
When the bottle is stopped, the inertia of
the sauce will cause the sauce to continue
moving downwards and out of the bottle. Chapter 6 Light and Optics Physics Form 4
are videos for certain Photograph 2.4
(f) When a car brakes abruptly, the driver and
B Optical fibre
passengers in the car are thrown forward Doctors use endoscope to see and examine organs
Outer cladding
due to inertia. Thus, seat belts are designed
(Low refractive index)
activities or experiments. Photograph 2.3 to prevent them from being thrown Normal Light signal inside the human body. Engineers use fibre optics
forward and injuring themselves.
to monitor performance of complex machinery.
Communication experts use fibre optics to send INFORMATION GALLERY
high speed data.
inner cladding
44 (High refractive index)
2.4.3
Figure 6.23 C Cat’s eye reflector
• Widely used in the telecommunication and • Can be used as safety devices for drivers at
medical fields. night.
• Made up of pure plastic or glass fibres. • Light rays from the headlight of a car will be
• The inner core of high refractive index is reflected by the reflector inside through total Additional information
surrounded by an outer cladding of lower internal reflection.
refractive index.
• When laser signal carrying information
such as telephone signals is introduced into related to the topic.
the inner core at one end, it will propagate
along the fibre undergoing a series of total
internal reflections until reaching the other
Form
end of the fibre. Hence the signal will be sent
5
Chapter 3 Electricity Physics with high speed and free from electrical noise
disturbances. Photograph 6.1 Cat's eye reflector on the road
3.4
Aim: To investigate how the resistivity of a wire, ρ affects its resistance.
Solve Problems Involving Total Internal Reflection
Problem statement: How the resistivity of a wire, ρ affects the resistance of the wire?
Example 3
Hypothesis: Materials with high resistivity gives higher resistance.
Figure 6.24 shows a light ray is traversing from air to a prism of refractive index 1.49.
Variables: (a) What is the critical angle of the prism?
(a) Manipulated: Resistivity of wire, ρ (b) Draw the light paths in the prism until it is emerging again into the air.
(b) Responding: Resistance of wire, R 45°
(c) Constant: Length of wire, temperature, area of cross-section of wire
ACTIVITY / EXPERIMENT (a) sin c = 1 (b) Figure 6.24 Chapter 7 Quantum Physics Physics Form 5
Solution
Apparatus and Materials:
50 cm constantan wire (s.w.g. 24), 50 cm copper wire (s.w.g. 24), 50 cm tungsten wire (s.w.g. 24), connecting
wires, three dry cells, switch, ammeter (0 – 1 A), voltmeter (0 – 5 V), rheostat and battery holder
Operational definition: n 1 C 6. The relationship between the momentum of
The resistance of the conductor, R, is given by the ratio of the reading of voltmeter to the reading of the sin c = 1.49 Example 1 45° particle, p and its wavelength, λ is
CHAP
ammeter. c = sin −1  1.49  Calculate the photon energy for light with λ = h
45°
3
sin 60°
45°45°are both
wavelengths 450 nm and 700 nm. Comp
Complete activity or Procedure: c = 42.2° photons. A 45° B —– p
1. An electrical circuit is set up as shown in
Figure 3.28.
Solution
Figure 6.25
2. A constantan wire is connected across Ammeter A The critical angle of the prisim is 42.2° Planck’s constant, h = 6.63 × 10 –34 J s which h is Planck’s constant (6.63 × 10 –34 J s)
Angle of incidence (i = 45°) larger than critical

experiment including results, Speed of light in vacuum, c = 3.00 × 10 8 m s –1
angle (c = 42.2°) at boundaries AB and AC.
terminals P and Q. The length of the wire
Wavelength, λ 1 = 450 × 10 –9 m
across P and Q is adjusted to be 30 cm long.
Total internal reflection occurred and the light
ray emerging from BC again into the air along
3. The switch is connected and the rheostat is
——— = p 2
E = hf = hc
the normal direction.
adjusted so that the ammeter gives a reading Rhesotat P Q Constantan wire Wavelength, λ 2 = 700 × 10 –9 m —— K = 1 —mv 2 × m —– ➞ K = (mv) 2 ——
2
data analysis, discussion Voltmeter Photon energy of 450 nm: λ which p = mv, p = ABBBB 2m 2m
of 0.5 A. The reading of voltmeter is taken
m
V
2mK
and recorded in Table 3.6.
CHAP
6
—————– 2
4. The constantan wire is removed and Steps
450 × 10 –9
2 and 3 are repeated for copper wire and Figure 3.28 E 1 = 6.63 × 10 –34 1 3.00 × 10 8
and conclusion to increase 6.2.3 6.2.4 = 4.42 × 10 –19 J 7. The larger the momentum of particle, the shorter BRILLIANT TIPS
tungsten wire.
the wavelength produced. The momentum of
195
Photon energy of 700 nm:
Table 3.6
Results:
E 2 = 6.63 × 10 –34 1 3.00 × 10 8 particle is p = mv, then p 2 —— = K
—————– 2
700 × 10 –9
2m
students' scientific skill. Wire Reading of ammeter, Reading of voltmeter, R = V — I / Ω = 2.84 × 10 –19 J λ = h —–– = ———— h
Resistance,
V / V
I / A
The shorter the wavelength of light, the higher
ABBBB
mv
2mK
the photon energy.
Useful tips for students
Constantan 0.5 6.3 12.6 where m is the mass of particle, v is the velocity
Form of particle and K is the kinetic energy of particle.
Copper 0.5 0.2 0.4 5
Wave-Particle Duality
to solve problems in the
Chapter 1 Force and Motion II Physics 8. Since the value of h is too small, the particle
1.2
wavelength to be detected. Thus, the wave
Tungsten 0.5 0.6 Solving Problems Involving Resultant Force and Resolution of Forces CHAP with large mass will have too short of de Broglie
1 characteristics cannot be observed.
Discussions: Example 4 Example 5 Wavelength simulation 9. In 1927, the presence of wave properties of
1. From Table 3.6, different conductor gives different resistance. http://bit.ly/39xNYqu related subtopic.
A wooden block is pulled by force, T that inclines Figure 1.17 shows the free body diagram of a electrons was confirmed through the electron
at an angle of 30° above the horizontal surface as
2. Constantan gives the highest resistance, followed by tungsten and copper gives the lowest resistance. block sliding down a smooth inclined plane. diffraction experiments.
shown in Figure 1.16.
3. Different material gives difference resistance because different material has different resistivity, ρ.
Resistance of a material increases when the resistivity of the material increases. R = 5 N T = 40 N 1. Light has wave properties because it shows the 10. Photograph 7.1 shows the diffraction pattern of
Normal reaction = 10 N
Wooden phenomena of diffraction and interference. electrons through a thin layer of graphite. The
block pattern in Photograph 7.2 resembles the light
Block
30° 2. Object has particle properties because it has diffraction pattern through an aperture.
3.2.3 F R = 18 N 335 momentum, kinetic energy and also collide with
each other.
3. Louis de Broglie introduced a hypothesis states
W = 25 N Weight,
60°
W = 20 N that all particles can exhibit wave characteristics
Figure 1.16 in year 1924.
Figure 1.17
(a) What are the magnitudes of the horizontal 4. However, it is experimentally difficult to show
component T x and vertical component T y of (a) Sketch and label the component of the weight
the wave characteristics of particles with large
the pulling force, T? of the block parallel to the inclined plane and
masses.
(b) Calculate the magnitude and direction of the the component of the weight of the block
resultant force acting on the block. perpendicular to the inclined plane. Photograph 7.1 Photograph 7.2
5. Thus, Louis de Broglie predicted that the wave
(c) Calculate the acceleration of the block if its (b) Calculate the resultant force acting on the 11. This observation proved de Broglie’s hypothesis. CHAP 7
characteristics can be shown by light particles
block.
EXAMPLE (a) Magnitude of the pulling force, (c) What is the acceleration of the block if its 477
mass is 1.8 kg.
such as electron, proton and neutron.
mass is 2.0 kg?
Solution
7.1.3
T = 40 N

T y Solution
T x = T cos 30° T (a)
= 40 cos 30° 30° Normal reaction = 10 N
= 36.64 N (to the right) T x
Example and complete T y = T sin 30° W y 60° W x
= 40 sin 30°
= 20 N (upward)
(b) Resultant of horizontal components
solution to enhance students' 60°

= T x – F R

= 36.64 + (–18)
= 16.64 N (to the right) (b) W x = 20 sin 60° = 17.32 N
Resultant of horizontal components
W y = 20 cos 60° = 10 N

understanding. = T y + R + W Resultant of the forces perpendicular to the
= 20 + 5 + (–25)
inclined plane = 10 + (–10)
= 0 N = 0 N
Resultant force on the block, F is 16.64 N to Resultant force on the block = 17.32 N
the right. (c) F = 17.32 N; Mass of the block, m = 2.0 kg
(c) F = 16.64 N; Mass of block, m = 1.8 kg F = ma
F = ma Acceleration, a = F —– m Acceleration of the block, a = F —– m
= 16.64 1.8 = 17.32
——––
——––
2.0
a = 9.24 m s –2 a = 8.66 m s –2
Try question 2 in Formative Zone 1.2
1.2.2 235
ii