Real Lab Skill: Measuring AC Voltage with a Multimeter

Multimeter digital boleh digunakan untuk mengukur voltan arus ulang alik (AC) yang dibekalkan oleh soket dinding.

A digital multimeter can be used to measure the AC voltage supplied by a wall socket.

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👀 Cara Membaca | Reading Technique

✅ Pilih mod AC Voltage (V~) pada multimeter.

✅ Select the AC Voltage (V~) mode on the multimeter.

✅ Pastikan julat voltan lebih tinggi daripada 240 V sebelum membuat pengukuran.

✅ Ensure the voltage range selected is higher than 240 V before measurement.

✅ Masukkan probe hitam ke terminal Neutral dan probe merah ke terminal Live.

✅ Insert the black probe into the Neutral terminal and the red probe into the Live terminal.

✅ Tunggu sehingga bacaan stabil sebelum merekod nilai voltan.

✅ Wait for the reading to stabilise before recording the voltage value.

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❌ Common Mistakes

❌ Memilih mod DC Voltage (V⎓) untuk mengukur soket AC.

❌ Selecting DC Voltage (V⎓) when measuring an AC outlet.

❌ Menyambung probe ke terminal multimeter yang salah.

❌ Connecting the probes to the wrong multimeter terminals.

❌ Menyentuh bahagian logam probe semasa pengukuran.

❌ Touching the metal parts of the probes during measurement.

❌ Tidak memeriksa julat voltan sebelum ujian dijalankan.

❌ Failing to check the voltage range before testing.

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⚠️ Safety / Handling

⚠️ Soket dinding membekalkan voltan tinggi dan boleh menyebabkan renjatan elektrik.

⚠️ A wall socket supplies high voltage and can cause electric shock.

⚠️ Pegang probe pada bahagian berpenebat sahaja.

⚠️ Hold probes by their insulated handles only.

⚠️ Jangan sentuh terminal logam semasa mengambil bacaan.

⚠️ Never touch exposed metal terminals during measurement.

⚠️ Lakukan pengukuran dengan berhati-hati dan di bawah pengawasan guru atau juruteknik makmal.

⚠️ Perform measurements carefully and under teacher or laboratory supervision.

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🎯 SPM Exam Tip

📌 Bekalan elektrik rumah di Malaysia ialah sekitar 240 V AC.

📌 The household electricity supply in Malaysia is approximately 240 V AC.

📌 AC bermaksud arus sentiasa berubah arah secara berkala.

📌 AC means the current continuously changes direction.

📌 Simbol pada multimeter:

📌 Common multimeter symbols:

✅ V~ = AC Voltage

✅ V⎓ = DC Voltage

📌 Jika mod yang salah dipilih, bacaan yang diperoleh mungkin tidak tepat.

📌 Choosing the wrong mode may result in an incorrect reading.

🔊 Checking Wire Continuity with a Multimeter

Ujian kesinambungan (continuity test) digunakan untuk menentukan sama ada terdapat laluan elektrik yang lengkap melalui dawai, suis atau komponen.

A continuity test is used to determine whether there is a complete electrical path through a wire, switch or component.

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👀 Cara Membaca | Reading Technique

✅ Pilih mod Continuity Test (🔊) pada multimeter.

✅ Select the Continuity Test (🔊) mode on the multimeter.

✅ Sentuhkan kedua-dua probe pada hujung dawai yang hendak diuji.

✅ Touch the two probes to opposite ends of the wire being tested.

✅ Jika multimeter berbunyi "beep", laluan elektrik adalah lengkap.

✅ If the multimeter beeps, the electrical path is complete.

✅ Jika tiada bunyi atau bacaan menunjukkan OL, dawai mungkin putus.

✅ If there is no beep or the display shows OL, the wire may be broken.

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❌ Common Mistakes

❌ Menjalankan ujian continuity ketika litar masih disambungkan kepada bekalan kuasa.

❌ Performing a continuity test while the circuit is still connected to a power supply.

❌ Menganggap semua wayar kelihatan elok mempunyai sambungan yang baik.

❌ Assuming a wire is good simply because it looks undamaged.

❌ Tidak memastikan probe menyentuh logam dengan baik.

❌ Failing to ensure proper contact between the probes and the metal conductor.

❌ Mengelirukan ujian continuity dengan pengukuran rintangan.

❌ Confusing a continuity test with a resistance measurement.

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⚠️ Safety / Handling

⚠️ Matikan bekalan kuasa sebelum melakukan ujian continuity.

⚠️ Switch off the power supply before performing a continuity test.

⚠️ Jangan gunakan mod continuity pada litar yang sedang beroperasi.

⚠️ Do not use continuity mode on a live circuit.

⚠️ Pastikan probe berada dalam terminal multimeter yang betul.

⚠️ Ensure the probes are connected to the correct multimeter terminals.

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🎯 SPM Exam Tip

📌 Continuity bermaksud terdapat laluan lengkap untuk arus mengalir.

📌 Continuity means there is a complete path for current to flow.

📌 Wayar yang baik mempunyai rintangan yang sangat rendah.

📌 A good wire has very low resistance.

📌 Ujian continuity sering digunakan untuk memeriksa:

📌 Continuity testing is commonly used to check:

✅ Connecting wires / Dawai penyambung
✅ Switches / Suis
✅ Fuse wires / Fius
✅ Circuit connections / Sambungan litar

📌 Jika multimeter berbunyi "beep", komponen biasanya masih berfungsi dengan baik.

📌 If the multimeter produces a beep, the component is usually still electrically connected.

Test Car Battery With a Multimeter

 

Connect the multimeter to the positive and negative battery terminals. If you don't have a voltage of around 12.6 volts, you may have a bad battery.  

Clinical thermometer

 

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

 

👀 Cara Membaca | Reading Technique

✅ Pastikan litar hanya lengkap apabila butang ditekan.

✅ Ensure the circuit is completed only when the button is pressed.

✅ Perhatikan perubahan pada mentol, ammeter atau galvanometer semasa kekunci ditekan.

✅ Observe changes in the bulb, ammeter or galvanometer when the key is pressed.

✅ Lepaskan kekunci selepas bacaan diperoleh jika eksperimen memerlukan arus mengalir seketika sahaja.

✅ Release the key after obtaining the reading when temporary current flow is required.

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❌ Common Mistakes

❌ Menekan kekunci terlalu lama sehingga komponen menjadi panas.

❌ Holding the key down for too long, causing components to heat up.

❌ Menganggap tapping key berfungsi seperti suis biasa yang kekal ON.

❌ Assuming a tapping key works like a normal switch that stays ON.

❌ Tidak melepaskan kekunci selepas bacaan diperoleh.

❌ Failing to release the key after the required reading is taken.

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⚠️ Safety / Handling

⚠️ Tekan kekunci hanya apabila bacaan hendak diambil.

⚠️ Press the key only when a reading is required.

⚠️ Elakkan menekan terlalu lama bagi mengurangkan pemanasan wayar dan komponen.

⚠️ Avoid prolonged pressing to reduce heating of wires and components.

⚠️ Pastikan terminal disambung dengan kemas sebelum eksperimen dijalankan.

⚠️ Ensure all terminals are securely connected before starting the experiment.

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🎯 SPM Exam Tip

📌 Tapping key biasanya digunakan dalam eksperimen yang melibatkan galvanometer, medan magnet dan induksi elektromagnet.

📌 A tapping key is commonly used in experiments involving galvanometers, magnetic fields and electromagnetic induction.

📌 Tujuannya ialah membenarkan arus mengalir untuk masa yang sangat singkat.

📌 Its purpose is to allow current to flow for a very short duration.

📌 Dalam jawapan SPM, nyatakan bahawa tapping key digunakan untuk melengkapkan litar secara sementara.

📌 In SPM answers, state that a tapping key is used to complete a circuit momentarily.

DIY Test tube brushes

DIY test tube brushes using contantant wire S.W.G 22

 

Test a Diode by Digital Multimeter

Forward Biased: When the Positive (Red) test lead is connected to the anode (+) and negative (Black) test lead is connected to the cathode (-) of diode. In Forward-biased, the diode acts like close switch and will pass the current through it like conductors.

Reverse Biased: If we do the reverse as mention above i.e. RED Test lead to cathode (-) and BLACK test lead to the Anode (+) of the diode. In revere-biased, the diode acts like open switch and will not let pass the current through it like resistor.

If multimeter does not show measurements I.e. if multimeter display “OL” reading in both direction (Forward-biased and reverse-biased), its mean diode is dead and acting as an open switch which doesn’t allow current to flow in it.

 

DIY Multimeter Alligator Clip Test Probe Leads

DIY Multimeter Alligator Clip Test Probe Leads

 

OPISOMETER

 

Opisometer an instrument used to measure curved lines on a map.

How is rheostat resistance measured?

Take a multimeter.

Tap the Terminal B and Terminal C and hold properly.

You get the resistance of the sliding contact.

Using DIY Multimeter Alligator Clip

 

Measure Resistance with a Digital Multimeter

Vintage Resistance Coils

Wire-wound resistors are made by having a metal wire wound round a non conductive core. Each end of the wire is then attached to terminals on either side of the core. The wire is typically protected by a layer of paint or other material to form a hard, protective surface.