DPDT Knife Switch: Function, Common Mistakes & SPM Physics Amali Tips

👀 Cara Membaca | Reading Technique

✅ Perhatikan kedudukan tuil suis sebelum merekod keadaan litar.

✅ Observe the switch lever position before recording the circuit condition.

✅ Pastikan suis berada sepenuhnya pada satu sisi dan membuat sentuhan yang baik dengan terminal.

✅ Ensure the switch is fully engaged on one side and makes proper contact with the terminals.

✅ Semak perubahan bacaan meter selepas suis ditukar kedudukan.

✅ Check for changes in meter readings after switching positions.

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❌ Common Mistakes

❌ Menganggap kedua-dua kedudukan suis menghasilkan litar yang sama.

❌ Assuming both switch positions produce the same circuit configuration.

❌ Sambungan wayar pada terminal yang salah.

❌ Connecting wires to the wrong terminals.

❌ Tidak menyemak kedudukan suis sebelum mengambil bacaan.

❌ Failing to check the switch position before recording readings.

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⚠️ Safety / Handling

⚠️ Matikan bekalan kuasa sebelum menukar sambungan wayar.

⚠️ Switch off the power supply before changing wire connections.

⚠️ Pastikan terminal bersih dan tidak longgar.

⚠️ Ensure the terminals are clean and securely tightened.

⚠️ Jangan menukar kedudukan suis dengan kasar kerana boleh merosakkan kenalan logam.

⚠️ Do not force the switch lever as it may damage the metal contacts.

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🎯 SPM Exam Tip

📌 DPDT sering digunakan untuk menukar arah arus dalam gegelung motor atau galvanometer.

📌 A DPDT switch is commonly used to reverse the direction of current in a motor coil or galvanometer.

📌 Dalam eksperimen fizik, perubahan kedudukan suis boleh menyebabkan arah pesongan galvanometer berubah.

📌 In physics experiments, changing the switch position may reverse the galvanometer deflection.

📌 Ingat: Double Pole = dua litar, Double Throw = dua pilihan sambungan.

📌 Remember: Double Pole = two circuits, Double Throw = two switching positions.

 

Gold Leaf Electroscope

This instrument is used for the detection of charge and measuring

static electricity.It works on the principle that the like charges repel

each other.

 

Static and Kinetic Friction

Static friction is what keeps the box from moving without being pushed, and it must be overcome with a sufficient opposing force before the box will move. Kinetic friction (also referred to as dynamic friction) is the force that resists the relative movement of the surfaces once they're in motion.

 

SLOTTED SET OF MASSES AND HANGER. Set of 9 slotted masses, one hanger

 

A Pulley as a Simple Machine

A pulley is a simple machine consisting of a wheel turning on an axle. Pulleys are often used singly and in combinations to do work.

 

Measuring a Resistor with a Digital Multimeter: Reading Technique & SPM Physics Tips

1K resistor

200 ohms resistor

Perintang (resistor) ialah komponen elektronik yang digunakan untuk menghadkan aliran arus elektrik dalam litar. Nilai rintangannya diukur dalam unit ohm (Ω).

A resistor is an electronic component used to limit the flow of electric current in a circuit. Its resistance is measured in ohms (Ω).

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👀 Cara Membaca | Reading Technique

✅ Pilih mod Resistance (Ω) pada multimeter.

✅ Select the Resistance (Ω) mode on the multimeter.

✅ Sentuhkan probe hitam dan probe merah pada kedua-dua kaki resistor.

✅ Touch the black and red probes to the two resistor leads.

✅ Tunggu sehingga bacaan menjadi stabil sebelum direkodkan.

✅ Wait until the reading becomes stable before recording it.

✅ Pastikan resistor tidak disambungkan kepada bekalan kuasa semasa pengukuran.

✅ Ensure the resistor is not connected to a power supply while measuring.

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❌ Common Mistakes

❌ Mengukur resistor semasa litar masih hidup.

❌ Measuring a resistor while the circuit is still powered.

❌ Memilih julat Ω yang tidak sesuai.

❌ Selecting an unsuitable resistance range.

❌ Menyentuh kedua-dua kaki resistor dengan jari semasa pengukuran.

❌ Touching both resistor leads with your fingers during measurement.

❌ Menganggap nilai resistor mesti tepat sama seperti nilai yang tertera.

❌ Assuming the measured value must be exactly the same as the labelled value.

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⚠️ Safety / Handling

⚠️ Matikan bekalan kuasa sebelum mengukur nilai resistor.

⚠️ Switch off the power supply before measuring resistance.

⚠️ Elakkan membengkokkan kaki resistor secara berlebihan.

⚠️ Avoid bending the resistor leads excessively.

⚠️ Simpan resistor dalam bekas yang sesuai selepas digunakan.

⚠️ Store resistors properly after use.

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🎯 SPM Exam Tip

📌 Resistansi diukur dalam unit ohm (Ω).

📌 Resistance is measured in ohms (Ω).

📌 Nilai sebenar resistor mungkin sedikit berbeza daripada nilai nominal.

📌 The actual resistance may differ slightly from the nominal value.

Example from the Photo

✅ Resistor 1 kΩ

Multimeter Reading: 1007 Ω

✅ Resistor 220 Ω

Multimeter Reading: 219.6 Ω

📌 Perbezaan kecil ini adalah normal kerana toleransi pembuatan.

📌 Small differences are normal due to manufacturing tolerance.

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🧠 SPM Concept Check

📌 Semakin besar nilai resistor:

📌 The higher the resistance:

✅ Semakin sukar arus mengalir.

✅ The more difficult it is for current to flow.

✅ Semakin kecil arus dalam litar.

✅ The smaller the current in the circuit.

Ohm's Law

V = IR

Where:

• V = Voltage / Voltan
• I = Current / Arus
• R = Resistance / Rintangan

 

HONG KONG SCIENTIFIC CO 香港科学仪器社 CONSTANTANT SWG 26

 

10 Ohms Rheostat

 

Griffin & George Limited-10 Ohms Rheostat

 

Pencil Lead Conducts Electricity

Pencils Lead Conduct Electricity and Act as Resistors Too.

The “lead” in a pencil isn't actually made from lead. It is made from a form of carbon called graphite. The graphite is mixed with clay and formed into long thin pencil lead.

 

Cable Peeler - kabel abisolierung

 

Foward current in diode.

A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction.

 

Heat - Bar and Gauge

After heating, the gauge shows that the bar has increased in length, which is called linear expansion

 

Sanwa Analog Multitesters YX360TRD

Case and instrument in one body, convenience to carry and store.

 

Heat - Ball and Ring

 

After heating, the metal balls expands and is unable to go through the ring.

Dynamics Trolleys, Wooden

Long wooden trolleys, mounted on threewheel.

 

GW Instek GPC-3030 Analog DC Power Supply

• Triple Output
• 5V, 3A Fixed output

 

British Optical Lens Co-Bi-Concave lens

 

SPM Physics Amali: Resistance Depends on Material

 

Constantant swg 28 vs Nichrome swg 28 vs Cooper swg 28

Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high temperatures.

🧵 Does the Type of Wire Affect Resistance?

Rintangan dawai bergantung pada jenis bahan yang digunakan. Bahan yang berbeza mempunyai kerintangan tentu (ρ) yang berbeza.

The resistance of a wire depends on the material used. Different materials have different resistivities (ρ).

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👀 Key Observations | Pemerhatian Penting

✅ Semua dawai mempunyai saiz yang hampir sama (SWG 28).

✅ All wires have approximately the same diameter (SWG 28).

✅ Panjang dawai yang digunakan adalah sama.

✅ The wires used have the same length.

✅ Bacaan arus berbeza apabila bahan dawai ditukar.

✅ The current reading changes when the wire material is changed.

✅ Ini menunjukkan setiap bahan mempunyai rintangan yang berbeza.

✅ This shows that different materials have different resistance values.

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❌ Common Mistakes

❌ Menganggap semua dawai mempunyai rintangan yang sama.

❌ Assuming all wires have the same resistance.

❌ Mengelirukan rintangan (R) dengan kerintangan tentu (ρ).

❌ Confusing resistance (R) with resistivity (ρ).

❌ Tidak mengawal panjang dan diameter dawai semasa membuat perbandingan.

❌ Failing to keep wire length and diameter constant during comparison.

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⚠️ Safety / Handling

⚠️ Matikan bekalan kuasa selepas mengambil bacaan.

⚠️ Switch off the power supply after taking readings.

⚠️ Dawai rintangan boleh menjadi panas apabila arus mengalir terlalu lama.

⚠️ Resistance wires may become hot if current flows for a long period.

⚠️ Elakkan menyentuh bahagian dawai yang panas.

⚠️ Avoid touching heated sections of the wire.

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🎯 SPM Exam Tip

📌 Untuk dawai yang mempunyai panjang dan diameter yang sama:

📌 For wires with the same length and diameter:

Copper → Lowest Resistance

Constantan → Higher Resistance

Nichrome → Highest Resistance

📌 Tembaga membenarkan arus mengalir dengan lebih mudah.

📌 Copper allows current to flow more easily.

📌 Nichrome mempunyai kerintangan tentu yang tinggi.

📌 Nichrome has a high resistivity.

📌 Sebab itu nichrome digunakan dalam elemen pemanas.

📌 That is why nichrome is commonly used in heating elements.

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🧠 SPM Concept Check

Formula yang perlu diingati:

Formula to remember:

R = ρL/A

di mana / where:

• R = Resistance
• ρ = Resistivity
• L = Length of wire
• A = Cross-sectional area

📌 Jika panjang dan diameter adalah tetap, rintangan bergantung kepada nilai ρ (resistivity).

📌 If length and diameter are fixed, resistance depends on ρ (resistivity).

A MODEL TRANSFORMER

Working Principle of A Transformer

• A transformer consists of a primary coil and a secondary coil wound on a soft iron core.
• When an alternating current flows in the primary coil, a changing magnetic flux is generated around the primary coil.
• The changing magnetic flux is transferred to the secondary coil through the iron core.
• The changing magnetic flux is cut by the secondary coil, hence induces an e.m.f. in the secondary coil.
• The magnitude of the output voltage can be controlled by the ratio of the number of primary coil and secondary coil.

 

⚡ Short Circuit (Litar Pintas)

 

What Is It? | Apakah Itu?

Litar pintas berlaku apabila arus elektrik mengalir melalui laluan yang mempunyai rintangan sangat rendah sehingga memintas komponen yang sepatutnya dilalui.

A short circuit occurs when electric current flows through a path with very low resistance, bypassing the intended component.

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👀 How to Identify | Cara Mengenal Pasti

✅ Sebuah komponen (contohnya mentol) dipintas oleh wayar.

✅ A component (e.g. a bulb) is bypassed by a wire.

✅ Arus memilih laluan dengan rintangan paling rendah.

✅ Current chooses the path of least resistance.

✅ Komponen yang dipintas biasanya tidak berfungsi.

✅ The bypassed component usually does not operate.

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❌ Common Mistakes

❌ Menyangka kedua-dua mentol masih berada dalam litar.

❌ Assuming both bulbs remain in the circuit.

❌ Tidak menyedari wayar telah memintas mentol.

❌ Failing to notice that the wire bypasses the bulb.

❌ Menghasilkan sambungan litar yang salah semasa eksperimen.

❌ Creating incorrect circuit connections during an experiment.

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⚠️ Safety Alert

⚠️ Litar pintas boleh menyebabkan arus yang sangat besar.

⚠️ A short circuit can cause a very large current.

⚠️ Wayar dan bekalan kuasa boleh menjadi panas.

⚠️ Wires and power supplies may become hot.

⚠️ Matikan bekalan kuasa dengan segera jika berlaku litar pintas.

⚠️ Switch off the power supply immediately if a short circuit occurs.

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🎯 SPM Exam Tip

📌 Mentol yang dipintas oleh wayar tidak akan menyala.

📌 A bulb bypassed by a wire will not light up.

📌 Arus lebih suka mengalir melalui wayar kerana rintangannya jauh lebih rendah daripada mentol.

📌 Current prefers flowing through the wire because its resistance is much lower than that of the bulb.

Audio Signal Generator AG-202A

Country: Japan

Manufacturer / Brand: Kenwood, Trio-Kenwood Inc.; Komagane

Year: 1970 ??

 

Diffraction Grating

To produce a bright and sharp interference pattern for light, a diffraction grating is used in preference to a Young's double slit.

A diffraction grating consists of many equally-spaced slits placed extremely close together, e.g., 300 lines/mm.

 

Plug Key: Function, Common Mistakes & SPM Physics Amali Tips

👀 Cara Membaca | Reading Technique

✅ Pastikan plug dimasukkan sepenuhnya sebelum mengambil bacaan.

✅ Ensure the plug is fully inserted before taking any reading.

✅ Semak bahawa litar lengkap dan meter menunjukkan bacaan yang stabil.

✅ Check that the circuit is complete and the meter shows a stable reading.

✅ Ambil bacaan hanya selepas semua sambungan dibuat dengan betul.

✅ Record readings only after all connections are properly secured.

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❌ Common Mistakes

❌ Plug tidak dimasukkan sepenuhnya menyebabkan litar tidak lengkap.

❌ The plug is not fully inserted, resulting in an incomplete circuit.

❌ Menganggap litar masih lengkap selepas plug ditanggalkan.

❌ Assuming the circuit remains complete after the plug is removed.

❌ Sambungan wayar yang longgar pada terminal.

❌ Loose wire connections at the terminals.

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⚠️ Safety / Handling

⚠️ Matikan bekalan kuasa sebelum memasukkan atau menanggalkan plug jika perlu mengubah sambungan litar.

⚠️ Switch off the power supply before inserting or removing the plug when modifying circuit connections.

⚠️ Pastikan terminal bersih dan bebas daripada kakisan.

⚠️ Ensure the terminals are clean and free from corrosion.

⚠️ Elakkan menarik wayar secara kasar semasa mengendalikan plug key.

⚠️ Avoid pulling the wires forcefully when handling the plug key.

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🎯 SPM Exam Tip

📌 Plug key biasanya digunakan untuk mengawal aliran arus semasa eksperimen dijalankan.

📌 A plug key is commonly used to control the flow of current during an experiment.

📌 Apabila plug dimasukkan, litar lengkap dan arus mengalir.

📌 When the plug is inserted, the circuit is complete and current flows.

📌 Apabila plug ditanggalkan, litar terbuka dan arus terhenti.

📌 When the plug is removed, the circuit becomes open and current stops flowing.

 

SPM Physics Amali: How to Identify a Series Circuit

Litar siri terdiri daripada komponen yang disambungkan dalam satu laluan sahaja. Arus yang sama mengalir melalui setiap komponen dalam litar.

A series circuit consists of components connected in a single path. The same current flows through every component in the circuit.

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👀 Key Observations | Pemerhatian Penting

✅ Semua komponen disambungkan dalam satu laluan yang berterusan.

✅ All components are connected in a single continuous path.

✅ Arus yang sama mengalir melalui setiap mentol.

✅ The same current flows through every bulb.

✅ Kedua-dua mentol biasanya lebih malap berbanding satu mentol sahaja.

✅ Both bulbs are usually dimmer compared to a single bulb.

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❌ Common Mistakes

❌ Menganggap voltan adalah sama pada setiap mentol.

❌ Assuming the voltage is the same across every bulb.

❌ Mengelirukan litar siri dengan litar selari.

❌ Confusing a series circuit with a parallel circuit.

❌ Sambungan wayar yang longgar menyebabkan litar terbuka.

❌ Loose wire connections causing an open circuit.

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⚠️ What Happens If One Bulb Fails?

⚠️ Jika satu mentol terbakar atau ditanggalkan, keseluruhan litar akan terputus.

⚠️ If one bulb burns out or is removed, the entire circuit is broken.

⚠️ Semua mentol lain akan padam.

⚠️ All other bulbs will go out.

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🎯 SPM Exam Tip

📌 Dalam litar siri:

📌 In a series circuit:

• ✅ Current is the same throughout the circuit.

• ✅ Arus adalah sama di semua bahagian litar.

• ✅ Total resistance increases when more bulbs are added.

• ✅ Jumlah rintangan bertambah apabila lebih banyak mentol ditambah.

• ✅ Bulb brightness decreases when more bulbs are connected.

• ✅ Kecerahan mentol berkurang apabila lebih banyak mentol disambungkan.

How is the voltmeter and ammeter connected in a circuit?

A voltmeter is connected in parallel with a device to measure its voltage, while an ammeter is connected in series with a device to measure its current.

 

 

SPM Physics Amali: Understanding Parallel Circuits

 

Light bulbs in parallel

💡 Light Bulbs in a Parallel Circuit (Litar Selari)

Litar selari terdiri daripada dua atau lebih cabang yang disambungkan merentasi bekalan kuasa yang sama. Setiap cabang menerima voltan bekalan yang penuh.

A parallel circuit consists of two or more branches connected across the same power supply. Each branch receives the full supply voltage.

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👀 Key Observations | Pemerhatian Penting

✅ Terdapat lebih daripada satu laluan untuk arus mengalir.

✅ There is more than one path for current to flow.

✅ Setiap mentol menerima voltan yang sama dengan sumber kuasa.

✅ Each bulb receives the same voltage as the power supply.

✅ Kedua-dua mentol menyala dengan lebih terang berbanding dalam litar siri.

✅ Both bulbs shine brighter compared to a series circuit.

✅ Jika satu mentol ditanggalkan, mentol yang lain masih menyala.

✅ If one bulb is removed, the other bulb remains lit.

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❌ Common Mistakes

❌ Menganggap arus adalah sama dalam setiap cabang.

❌ Assuming the current is the same in every branch.

❌ Mengelirukan litar selari dengan litar siri.

❌ Confusing a parallel circuit with a series circuit.

❌ Menyangka semua mentol akan padam apabila satu mentol rosak.

❌ Assuming all bulbs will go out when one bulb fails.

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⚠️ Safety / Handling

⚠️ Pastikan setiap cabang disambungkan dengan betul pada terminal bekalan kuasa.

⚠️ Ensure each branch is connected correctly to the power supply terminals.

⚠️ Elakkan sambungan wayar yang longgar kerana boleh menyebabkan bacaan tidak stabil.

⚠️ Avoid loose wire connections as they may cause unstable readings.

⚠️ Matikan bekalan kuasa sebelum mengubah susunan litar.

⚠️ Switch off the power supply before modifying the circuit.

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🎯 SPM Exam Tip

📌 Dalam litar selari:

📌 In a parallel circuit:

V₁ = V₂ = V₃

✅ Voltan adalah sama pada setiap cabang.

✅ Voltage is the same across every branch.

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📌 Arus daripada sumber dibahagikan kepada beberapa cabang.

📌 Current from the source is divided among the branches.

I = I₁ + I₂ + I₃

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📌 Jika satu mentol ditanggalkan, cabang lain masih lengkap.

📌 If one bulb is removed, the other branches remain complete.

📌 Sebab itu lampu rumah disambung secara selari.

📌 That is why household lighting circuits are connected in parallel.

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🔍 How to Identify a Parallel Circuit Quickly

✅ Mempunyai cabang atau simpang wayar.

✅ Has branches or junctions.

✅ Terdapat lebih daripada satu laluan arus.

✅ More than one path for current flow.

✅ Komponen boleh berfungsi secara bebas.

✅ Components can operate independently.

✅ Satu mentol rosak tidak menjejaskan mentol yang lain.

✅ One failed bulb does not affect the others.