Provide any two values to solve for the third.
React to supply surges by nudging resistance so I = V ÷ R stays inside the safe operating window. Every steady second reinforces how current responds to voltage swings and resistor sizing.
Controls: tap/drag left side to drop resistance, right side to raise it. Keyboard fallback: ← and →. Pause when switching tabs — the circuit resumes when you click Play Again.
It is one thing to read that voltage is proportional to current; it is another to watch the relationship unfold before your eyes. Many learners struggle to internalize abstract formulas, yet a graph makes them tangible. By embedding a responsive HTML5 canvas directly in this calculator, the linear bond between voltage and current becomes a vivid line whose slope equals the resistance. As you change the inputs, the line tilts and the highlighted operating point slides smoothly along it. This kind of immediate feedback builds intuition: doubling the voltage is no longer a mere statement but a line twice as steep and a point twice as high. Interactive visualization bridges the gap between symbolic algebra and physical circuits, reinforcing concepts through sight and experimentation.
At the heart of the graph lies the fundamental equation
.
This deceptively simple statement spawns three companion forms by solving for each variable:
Because the relationship is linear, plotting voltage against current yields a straight line. The slope of that line is resistance. On the canvas, current is placed on the horizontal axis and voltage on the vertical axis so that higher resistance appears as a steeper incline. When you supply any two quantities, the script calculates the third and rescales the axes so the full line and the specific operating point fit neatly in view. Behind the scenes, every pixel on the screen corresponds to values determined by the parametric equations with running from zero to the displayed maximum.
Consider a scenario in which you know the resistance of a device and the voltage of your power source. Suppose a resistor of is connected to a V battery. Entering 6 for voltage and 200 for resistance, leaving current blank, prompts the calculator to compute A, or 30 mA. The canvas responds instantly: a straight orange line appears, rising gently with a slope corresponding to 200 Ω. A blue marker pinpoints the operating point at . Resize the browser window or adjust inputs and the graph gracefully adapts, preserving the relationships. Watching the point glide along the line helps cement the idea that every combination of voltage and current for this resistor must sit on that same incline.
Different resistances and supply voltages lead to markedly different currents. The table below explores four common situations. Each row lists the expected current along with a rough power dissipation, computed via .
Voltage (V) | Resistance (Ω) | Current (A) | Power (W) |
---|---|---|---|
5 | 100 | 0.050 | 0.25 |
9 | 300 | 0.030 | 0.27 |
12 | 600 | 0.020 | 0.24 |
24 | 1200 | 0.020 | 0.48 |
Try replicating these entries in the form to see each point appear on its respective line. By comparing the slopes, you can infer how doubling resistance halves current for the same voltage, and how power responds to the interplay.
The axes meet at the origin because zero current implies zero voltage. Every point on the line represents a valid operating state for the chosen resistance. When the slope is gentle, a small increase in current causes only a modest rise in voltage; this signifies a low resistance. A steep slope indicates that even a tiny current requires a large voltage push—characteristic of a high resistance or a partially open circuit. The blue dot highlights your actual inputs, while the rest of the line portrays what would happen if you altered either quantity while keeping resistance fixed. Text underneath the canvas summarizes the situation in words so screen readers and users on low-vision modes still grasp the essence.
Real components do not always obey perfect linearity. The graph assumes the resistor is ideal and temperature remains constant. In practice, heating can change resistance, and some materials exhibit non-ohmic behavior. Wires have small but nonzero resistance, and measurement tolerances can introduce error. At extreme voltages or currents, breakdown phenomena occur, and the straight-line model collapses. Nevertheless, for the vast majority of hobby and educational circuits, Ohm’s law is an excellent approximation. Seeing the straight line helps you recognize when an actual device deviates: if an LED’s current versus voltage curve bends sharply, that tells you Ohm’s law alone cannot describe it. The visualization encourages healthy skepticism, reminding you to check data sheets and consider power limits.
In fields from audio engineering to renewable energy systems, understanding and visualizing Ohm’s law guides practical decisions. The canvas here is more than decoration—it is a window into how components behave and how design choices influence performance. Combine it with experimentation: measure a resistor with a multimeter, enter the values, and compare the predicted point with real measurements. The more you interact, the deeper your intuition for electronic behavior will grow.