Nguyễn Đình ThuyênAn open notebook
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Play & learn

Move a value. See an idea.

Small, local experiments. Change one thing and notice what changes with it.

These simplified models are for learning. They do not configure equipment or replace engineering calculations.

01 / IPv4

An address finds its neighbourhood.

Network
Broadcast
Host range
Usable addresses

/31 assumes a point-to-point link; /32 represents one host. This calculator does not assign addresses or assess routability.

02 / V = I × R

A small circuit, a clear relationship.

V = I × R
Current
Power

Ideal, steady DC resistor only. Marker rate is proportional to conventional current, not actual electron speed. No heating, tolerances, wiring or battery limits are modelled.

03 / c = 299,792.458 km/s

Even light needs time.

SourceDestination

1 AU = 149,597,870.7 km exactly, approximately the mean Earth–Sun distance. 2 AU = 299,195,741.4 km. Light needs about 8 min 19 s per AU.

A 0.6 s pause at the destination separates each pulse; it is not part of light travel time.

One-way light time
1.282221 s
Time on screen
Simulated time
0
Ready
Ready

Straight-line travel in vacuum: t = d / c. The line always represents the selected distance; objects are not drawn to scale. Radio routing and processing add delay.

04 / Foundations

Can you still get back in?

Try a paper scenario. Your phone is unavailable. Choose the next step that gives useful evidence.

What would you check first?