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Physics F5C4

How does induction cooker work?
- High frequency alternating current in the coil
- This produces a changing magnetic field
- Eddy current is induced on the bottom of the pan
- Eddy currents produce heat on the pan

#physics #f5
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Physics F5C6
Nuclear energy essay

How to handle radioactive source

Use forceps
- Distance btwn source & body is far
Use mask and goggles
- Radiation unable to penetrate the eyes
Use lead box
- prevent radiation leakage to surroundings
Keep exposure time short
- body isn't exposed to dangerous radiation too much
Wear film badge
- detect amount of radiation exposed

#physics #f5
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Frequently asked question in Physics F5C5

What's the function of fluorescent screen?
- to convert kinetic energy of the electron to light energy

What's the function of vacuum?
- to prevent collision btwn electrons & air molecules

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Physics F5C5 transistors

1)Amplifier
•The function of microphone: convert sound energy to electric energy
• The function of loud speaker: convert electric energy to sound energy
- When a person speaks through a microphone, the sound waves are converted into an alternating current
- A small change in base current will cause a big change in the collector current
- The loudspeaker thus receives a large alternating current from the collector current and converts it into loud sound.
- The capacitor blocks a steady current (direct current) from flowing into the transistor and microphone

2)Light controlled switch
- At night, the light dependent resistor resistance is very high compared to resistor R
- Base voltage increase > Vbe
- Base current increase
- High enough to switch on the transistor
- The bulb light up

• What if you want the bulb to light up in the morning?
Ans: interchange the position btwn LDR and resistor R

3) Fire Alarm Automatic Switch
- When the thermistor increase, it has smaller resistance
- Thus, the voltage across the resistor R increases and becomes very high
- Base current increases
- Collector current increases
- The bulb light up

#physics #f5
🦋*ੈ✩‧₊˚ 『 @serenenotes 』

Physics F4C4 Frequent Asked Questions

Why is mercury used in thermometer ?
- Expand uniformly
- Opaque
- Doesn't stick to the glass wall

What is the function of constriction in thermometer?
- to avoid mercury returns back to the bulb
• When we took out the thermometer from the mouth, the temperature will drop
• With constriction, the temperature won't drop.
• Thus, we can read the temperature easily

What are the characteristics of a good thermometer?
1) have thin capillary tube
- increase sensitivity
2) thin wall of bulb
- absorb heat faster
3) small size of bulb
- absorb heat faster

#physics #f4
🦋*ੈ✩‧₊˚ 『 @serenenotes 』

Physics F4C4

Working principle of car radiator system
- combustion of fuel in the engine produces a lot of heat
- the pump forces the water to pass through the hot engine block areas and the water absorb heat
- the specific heat capacity of water is high
- it absorbs a lot of hear
- hot water flows to the radiator and is cooled through a cooling fin.

#physics #f4
🦋*ੈ✩‧₊˚ 『 @serenenotes 』

Physics F4C4 essay

Modifications of grill
i) outer coating on grill body : ceramic / porcelain
- high specific heat capacity
ii) additional tool on the grill 1 : lid
- reduce heat loss
iii) additional tool on the grill 2 : fan
- supply more oxygen

#physics #f4
🦋*ੈ✩‧₊˚ 『 @serenenotes 』

Physics F5C2 Archimedes' Principle

Essay related to Hydrometer

Thin and long stem
- bigger range of liquid density
Made of glass
- not easy to erode
Large bulb
- greater buoyant force
High density of lead granules
- ensure the hydrometer always upright

#physics #f5
🦋*ੈ✩‧₊˚ 『 @serenenotes 』

💡Physics with Heera

📡Chapter 3 : Electricity

! IMPORTANT DEFINITIONS !
Part 1

🔎E.H.T
👉🏻Extra high tension

🔍Electric field
👉🏻The REGION around a charged particle where any charge in the region will experience an electric force.

🔍Electric field strength, E
👉🏻Electric force acting on a unit postive charge placed at a point.

🔍Current, I
👉🏻The rate of flow of charge, Q in a conductor

🔍Potential difference, V
👉🏻The work done, W in moving one coulumb of charge, Q from one point to another.
V = W/Q or
V = E/Q

🔍Resistance
👉🏻Ratio between potential difference, V and current, I.
R = V/I

🔍Rheostat
👉🏻Control the current flow

🔍s.w.g.
👉🏻Size wire gauge

#physics #c3 #f5
#heera

🦋*ੈ✩‧₊˚ 『 @serenenotes 』

💡Physics with Heera

! IMPORTANT DEFINITIONS !
Part 2

🔍Resistivity of a conductor, p
👉🏻Measure of a conductor's ability to oppose the flow of the electric current.

🔍Superconductors
👉🏻Materials that conduct electricity without any resistance.

🔍Critical temperature, Tc
The temperature when the resistivity of a superconductor becomes ZERO.

🔍Electromotive force (e.m.f.)
Energy transferred or work done by an electrical source to move one coulumb of charge in a complete circuit.

🔍Voltage drop
Value of potential difference across the circuit, V is SMALLER than the e.m.f. of the dry cell
V < e.m.f.

🔍Internal resistance, r of dry cell
The resistance caused by electrolytes in the dry cell
🧠Apa effects??
😿Loss of energy in the form of heat in dry cell
😿V < e.m.f. ---- (voltage drop👀)


#physics #c3 #f5
#heera

🦋*ੈ✩‧₊˚ 『 @serenenotes 』

💡Physics with Heera👩‍🏫

Chapter 1 - Force and Motion II
🌷1.4 Elasticity

Elasticity
👉The property of material that enables an object to return to its original shape and size after the force applied on it is removed

Hooke's Law
👉The extension of spring (x) is directly proportional to the force applied on the spring (F) provided the elastic limit of the spring is not exceeded

k is spring constant

F=kx

#physics #f5 #c1
#heera

🦋*ੈ✩‧₊˚ 『 @serenenotes 』

💡Physics with Heera👩‍🏫

Important Definitions !

🌷Chapter 1 - Force and Motion II

1⃣Weight
👉The gravitational force acting on an object

2⃣Force
👉A push or pull upon an object

3⃣Resultant Force
👉The single force that represents the vector sum of 2 or more forces acting on an object
👉The total force acting on the object

4⃣Free body diagram of an Object
👉Diagram that shows all the forces acting on that object only

5⃣Newton's 2nd Law of Motion (F=ma)
👉The rate of change of momentum is directly proportional to the force
👉Acts in the direction of the applied force

6⃣Acceleration (a= v-u / t)
👉Rate of change of velocity

7⃣Resolution of Forces
👉The process of resolving a force into 2 components
- Vertical and horizontal

8⃣Equilibrium of Forces or (Forces in Equilibrium)
👉The force acting on it produce a zero resultant force

9⃣Elasticity
👉The property of material that enables an object to return to its original shape and size after the force applied on it is removed

🔟Hooke's Law
👉The extension of a spring (x) is directly proportional to the force applied on the spring provided the elastic limit of the spring is not exceeded.

#physics #f5 #c1
#heera

🦋*ੈ✩‧₊˚ 『 @serenenotes 』

💡Physics with Heera👩‍🏫

Chapter 1 - Force and Motion II
🌷1.4 Elasticity

Elasticity
👉The property of material that enables an object to return to its original shape and size after the force applied on it is removed

Hooke's Law
👉The extension of spring (x) is directly proportional to the force applied on the spring (F) provided the elastic limit of the spring is not exceeded

k is spring constant

F=kx

#physics #f5 #c1
#heera

🦋*ੈ✩‧₊˚ 『 @serenenotes 』

💡Physics with Heera

4.1 Force on a Current-carrying Conductor in a Magnetic Field

🧲When a current-carrying conductor is placed in a magnetic field, the conductor will experience FORCE

🧲Direction of the force depends on :
🔋Direction of the current
🔋Direction of the magnetic field

🧲Force on a current-carrying conductor in a magnetic field is produced by?
👉The interaction between 2 magnetic fields
● magnetic field from the electric current in the conductor
●magnetic field from the permanent magnet

🫂The 2 magnetic fields combine to produce resultant magnetic field that is known as CATAPULT FIELD
🍁The PATTERN of the catapult field = direction of the force acting on the conductor

What is Catapult field? (Pg 138)

👉A resultant magnetic field produced by the interaction between the magnetic field from a current-carrying conductor and magnetic field from a permanent magnet

~ to be continued ~
#physics #c4 #f5
#heera

🦋*ੈ✩‧₊˚ 『 @serenenotes 』