IP Topics

01 August

Lens Ray Diagram

Seng Kwang Tan IP3 07 Light, Simulations 0 Comments

I initially wanted to modify my GeoGebra applet on the converging lens ray diagram to include the case for infinitely far objects but thought I should give Claude.ai a try to generate one using javascript. It went very smooth. I merely took a screenshot of the original GeoGebra applet for reference, and used the following prompts: “Refer to this geogebra applet and make a html5 version. The user can change the focal length, the lens position and object height using mouse clicks or touchscreen drags. Keep the size responsive. Keep the buttons as overlays.” There were a few iterations after that but the first iteration was already good enough as a minimum-viable product.

This is the end product:

Access the full version here.

25 July

Lennard-Jones Potential

Seng Kwang Tan AI, IP4 17 Kinetic Model of Matter 1 Comment

Open simulation here. This was built using Claude.AI, which I notice, is better at suggesting UI features than ChatGPT or Gemini. I did not put too much effort into this as I only wanted to explain to upper sec IP students why intermolecular forces need not always be attractive, as well as to link it to the potential energy between particles in the kinetic particle model of matter.

13 June

Charging Two Conductors by Induction Simulation

Seng Kwang Tan IP4 10 Static Electricity, Javascript, Simulations 0 Comments
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Following a previous simulation on charging by induction, this simulation allows students to investigate the effects of performing the actions of bringing or removing a charged rod near a pair of conducting cans that can be placed in contact or separated-in any order they choose. Each sequence produces a distinct outcome: the cans may finish with opposite charges or both neutral. The simulation makes the invisible electron shifts clear, helping learners see exactly when charge flows between cans and when it merely redistributes inside a single conductor.

The above screenshot shows one possible state of the charges after a particular sequence of buttons are clicked. Could you figure out what is the order of buttons pressed?

12 June

Charging by Induction Simulation

Seng Kwang Tan IP4 10 Static Electricity, Simulations 0 Comments
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In the topic of Static Electricity, charging by induction often presents a challenge for students. The process involves several invisible steps — the movement of electrons, the effect of grounding, and the lasting net charge after removing the influencing object. To bridge this gap between theory and understanding, I have created this interactive simulation to help students visualise the interactions and changes. Students can be asked to predict what will happen using various button sequences to help challenge students’ preconceptions about electric charge and behaviour during induction.

Charging by Induction Javascript Simulation

Refer to the scenario above. What will happen next if we:
a) Remove the earth wire before removing the rod, or
b) Remove the rod before removing the earth wire?

09 June

Induced Magnetism Simulation

Seng Kwang Tan IP4 14 Magnetism, Simulations 0 Comments
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When certain materials like iron, steel, or nickel are placed near a magnet or inside a solenoid (coil of wire with current), they can become temporary magnets. This process is called induced magnetism.

You can explore this using the simulation above.

Use the Permanent Magnet
Click “Use Permanent Magnet” and drag the red-blue magnet near the grey block.
As you move it close, the arrows start to align — this shows that a magnetic field is aligning the domains, turning the material into a temporary magnet.

Try the Solenoid (Electromagnet)
Click “Use Solenoid”. This simulates a current-carrying coil.
Again, when it’s brought near the material, you’ll see the arrows align — the material becomes magnetized by the magnetic field of the solenoid.

Remove the Field
Click “Remove Magnetic Field” — the arrows scatter back to random directions. This shows that induced magnetism is temporary unless the material is a permanent magnet itself.

09 June

Temperature and Pressure of Gas

Seng Kwang Tan 08 Temperature and Ideal Gases, IP4 17 Kinetic Model of Matter, Simulations 0 Comments

This interactive HTML5 simulation models the behavior of gas particles in a fixed-volume container, allowing users to explore the relationships between temperature, pressure, and particle motion. Users can adjust the temperature using a slider, which directly affects the speed of the particles based on kinetic theory. As particles collide with the container walls, they briefly turn red to visually indicate wall interactions—collisions that contribute to pressure. A real-time pressure gauge on the side rises proportionally with temperature, consistent with the ideal gas law.

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500 K

According to the kinetic model of matter, gases consist of a large number of small particles (atoms or molecules) moving randomly and continuously in all directions. These particles have kinetic energy, which depends on temperature.

As temperature increases, the average kinetic energy of the gas particles increases. This means the particles move faster. Since pressure arises from particles colliding with the walls of the container, faster-moving particles collide more frequently and with greater force. These more energetic collisions result in a higher pressure on the container walls.

In a fixed volume, this explains why pressure is directly proportional to temperature (in kelvin), a relationship described by: P∝T
(if volume and number of particles are constant)