SPM Physics: AHA! Concave Lens = Diverging Lens

 

Why does a concave lens spread out light rays? The answer lies in its shape and optical behavior:

• Thinner at the centre, thicker at the edges.

• Parallel rays entering the lens are refracted away from the principal axis.

• The rays appear to diverge from a virtual focal point.

Exam tip: don’t just memorize “concave lens.” Write the scoring clue: parallel rays diverge after refraction. That’s the keyword examiners look for.

AHA! Concave lens spreads light. Not by sight, but by INSIGHT!

#AHAPhysicsMoments #CikguLimCY #PhysicsInEverydayLife #100DaysOfPhysics #SeeWithPhysicsEyes #PhysicsWithInsight

Magnetic Field Visualiser-Seeing the Invisible

 

Photographed during one of my Physics lessons, this classic apparatus allows us to see something that is normally invisible: a magnetic field.

A permanent magnet is placed inside a transparent container filled with magnetic particles suspended in liquid. As the magnet moves, the particles instantly align themselves along the magnetic field lines, creating patterns that reveal the shape of the otherwise invisible field.

What appears to be a simple black cluster is actually a map of magnetism in action.

A Teaching Reflection

Looking at these photographs, I was reminded that Physics often asks students to understand things they cannot see.

Today, students can simulate magnetic fields on a screen with a few clicks.

Yet there is something uniquely powerful about watching real particles physically rearrange themselves around a magnet.

No animation.

No simulation.

No AI-generated model.

Just matter responding to nature's laws in real time.

Sometimes the most memorable learning happens when an invisible idea suddenly becomes visible.

AHA Moment

AHA! The magnetic field was always there. The particles didn't create it — they revealed it. Not by sight, but by INSIGHT! 

Can You See a Magnetic Field? | A Classic Physics Demonstration

 

A magnetic field viewer allows us to observe something that is normally impossible to see with our eyes: a magnetic field.

Pemerhati medan magnet membolehkan kita melihat sesuatu yang biasanya tidak dapat dilihat dengan mata kasar, iaitu medan magnet.

---

👀 What Can We Learn From This Photo?

✅ The magnetic particles gather most densely at both ends of the bar magnet.

✅ Zarah magnet berkumpul paling padat di kedua-dua hujung magnet bar.

✅ The particles form curved patterns around the magnet.

✅ Zarah-zarah membentuk corak melengkung di sekeliling magnet.

✅ The magnetic field is strongest near the poles.

✅ Medan magnet paling kuat berhampiran kutub magnet.

✅ The centre of the magnet shows a weaker field pattern compared to the poles.

✅ Bahagian tengah magnet menunjukkan corak medan yang lebih lemah berbanding kawasan kutub.

---

🔬 Physics Behind It

Magnetic fields are invisible.

Medan magnet tidak dapat dilihat.

When tiny magnetic particles are placed near a magnet, they become temporarily magnetised and align themselves with the magnetic field.

Apabila zarah magnet yang kecil diletakkan berhampiran magnet, zarah tersebut akan dimagnetkan sementara dan menyusun diri mengikut arah medan magnet.

The resulting pattern reveals the shape of the magnetic field surrounding the magnet.

Corak yang terhasil menunjukkan bentuk medan magnet di sekeliling magnet tersebut.

AHA Moment

AHA! The magnetic field was always there. The particles didn't create it — they revealed it. Not by sight, but by INSIGHT!

The Heart of an Electric Motor: A Student-Built Motor Coil

 

A motor coil is the heart of a simple electric motor. When electric current flows through the coil inside a magnetic field, a force is produced that can make the coil rotate.

Gegelung motor merupakan bahagian terpenting dalam motor elektrik ringkas. Apabila arus mengalir melalui gegelung dalam medan magnet, satu daya akan terhasil dan menyebabkan gegelung berputar.

---

👀 What Can We Learn From This Photo?

✅ The coil is carefully wound from enamel-coated copper wire.

✅ Gegelung ini dililit dengan teliti menggunakan dawai kuprum bersalut enamel.

✅ The loops are arranged neatly to maintain balance during rotation.

✅ Lilitan disusun dengan kemas untuk memastikan keseimbangan semasa berputar.

✅ The two straight ends act as electrical contacts and support the rotating coil.

✅ Dua hujung dawai yang lurus berfungsi sebagai sentuhan elektrik dan sokongan kepada gegelung yang berputar.

✅ This coil will later be placed between permanent magnets to form a simple electric motor.

✅ Gegelung ini kemudiannya akan diletakkan di antara magnet kekal untuk membentuk motor elektrik ringkas.

---

🎯 SPM Physics Connection

📌 A current-carrying coil produces a magnetic field.

📌 Gegelung yang membawa arus menghasilkan medan magnet.

📌 When placed between magnetic poles, the coil experiences a turning force.

📌 Apabila diletakkan di antara kutub magnet, gegelung mengalami daya putaran.

📌 This is the principle behind electric motors.

📌 Inilah prinsip asas motor elektrik.

📌 Electrical Energy → Mechanical Energy

📌 Tenaga Elektrik → Tenaga Mekanik

---

 A Small Discovery in the Physics Lab

Photographed during one of my Physics lessons, this motor coil was not manufactured in a factory. It was carefully hand-wound by a student.

Looking at it, it is easy to see only a piece of copper wire. But in reality, every electric motor begins with something very similar to this. From classroom projects to industrial machines and electric vehicles, the same idea remains unchanged.

AHA! Every electric motor starts with a simple coil of wire. Not by complexity, but by CREATIVITY!

#AHAPhysicsMoments #CikguLimCY #PhysicsInEverydayLife #100DaysOfPhysics #SeeWithPhysicsEyes #PhysicsWithInsight

How Does an Electric Motor Work? | Motor Effect Explained for SPM Physics

A demonstration electric motor is a teaching apparatus used to show how electrical energy is converted into mechanical energy through the motor effect.

Motor elektrik demonstrasi ialah alat pengajaran yang digunakan untuk menunjukkan bagaimana tenaga elektrik ditukarkan kepada tenaga mekanik melalui kesan motor.

---

👀 Key Components | Ciri-ciri Utama

✅ Permanent Magnets

✅ Coil / Armature

✅ Axle / Pivot

✅ Terminals / Connecting Wires

✅ Magnet Kekal

✅ Gegelung / Angker

✅ Paksi / Pivot

✅ Terminal / Wayar Penyambung

---

🔍 What Can We Learn From This Photo?

✅ Two permanent magnets create a magnetic field around the coil.

✅ Dua magnet kekal menghasilkan medan magnet di sekeliling gegelung.

✅ The coil is free to rotate about the axle.

✅ Gegelung bebas berputar pada paksinya.

✅ When electric current flows through the coil, magnetic forces act on opposite sides of the conductor.

✅ Apabila arus elektrik mengalir melalui gegelung, daya magnet bertindak pada kedua-dua sisi konduktor.

✅ These forces produce a turning effect that causes rotation.

✅ Daya ini menghasilkan kesan putaran yang menyebabkan gegelung berputar.

✅ This is the same principle used in household fans, mixers and electric vehicles.

✅ Prinsip yang sama digunakan dalam kipas, pengisar dan kenderaan elektrik.

---

❌ Common Mistakes

❌ Assuming the magnets alone make the motor spin.

❌ Menganggap magnet sahaja menyebabkan motor berputar.

❌ Forgetting that current must flow through the coil.

❌ Terlupa bahawa arus mesti mengalir melalui gegelung.

❌ Confusing a motor with a generator.

❌ Mengelirukan motor dengan generator.

❌ Thinking the motor creates energy.

❌ Menganggap motor menghasilkan tenaga.

---

⚠️ Safety / Handling

⚠️ Use only a low-voltage power supply.

⚠️ Gunakan bekalan kuasa voltan rendah sahaja.

⚠️ Keep fingers away from moving parts during operation.

⚠️ Jauhkan jari daripada bahagian yang bergerak semasa operasi.

⚠️ Switch off the power supply before adjusting the setup.

⚠️ Matikan bekalan kuasa sebelum membuat pelarasan.

---

🎯 SPM Physics Connection

📌 A current-carrying conductor experiences a force in a magnetic field.

📌 Konduktor yang membawa arus mengalami daya dalam medan magnet.

📌 This phenomenon is known as the Motor Effect.

📌 Fenomena ini dikenali sebagai Kesan Motor.

📌 The direction of motion can be predicted using Fleming's Left-Hand Rule.

📌 Arah pergerakan boleh ditentukan menggunakan Petua Tangan Kiri Fleming.

📌 Electric motors convert electrical energy into mechanical energy.

📌 Motor elektrik menukarkan tenaga elektrik kepada tenaga mekanik.

 AHA! Every spinning fan, blender and electric vehicle begins with the same three ingredients: a current, a magnetic field and a force. Not by motion, but by MAGNETISM IN ACTION!

#AHAPhysicsMoments #CikguLimCY #PhysicsInEverydayLife #100DaysOfPhysics #SeeWithPhysicsEyes #PhysicsWithInsight