IV Graph Quiz: Test Your Understanding of Current Voltage Graphs

Power is defined as the rate at which work is done or energy is transferred. The unit of power in the International System of Units (SI) is the watt, symbolized as "W." One watt is equivalent to one joule per second, indicating that when one joule of energy is used in one second, one watt of power is being exerted. This unit is commonly used in various fields, including physics and engineering, to quantify the efficiency and performance of machines, electrical devices, and energy consumption.

Graphs show whether resistance is constant. Power relations explain why current limits and component ratings matter.

Ohm’s law is not universal for every component. It works well for many conductors at constant temperature and moderate fields.

Even metals change resistance with temperature. Significant heating can bend the i–v relationship away from a perfect line.

An ohmic conductor is a material that adheres to Ohm's Law, which states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature remains constant. This relationship is represented by the equation V = IR, where V is voltage, I is current, and R is resistance. Ohmic conductors exhibit a linear relationship between voltage and current, meaning their resistance remains constant regardless of the applied voltage or current level. Common examples include metals like copper and aluminum.

If (i) is plotted against (v), slope is (i/v = 1/r) for ohmic behavior. This is called conductance.

Using (p=i^2r), (p = 2^2 * 10 = 4 * 10 = 40) w. This indicates significant heating.

With fixed (v), current is (i=v/r). Lower current reduces (i^2r) heating in many parts of a circuit.

Fuses are designed to break the circuit when current exceeds a safe value. This prevents overheating and damage.

Moving charges collide with atoms and lose energy. That energy becomes internal thermal energy, heating the resistor.

Ohmic conductors have constant resistance, so (v ∝ i). This gives a straight-line i–v graph through the origin.

With (p=i^2r), doubling (i) multiplies power by (2^2=4). This is why high currents can overheat wires.

Substitute (v=ir) into (p=vi) to get (p=i^2r). This shows heating increases strongly with current.

Power is the rate of energy transfer. In circuits, (p=vi) expresses how much energy per second is delivered.

You can compute a ratio (v/i) at any point. The key is that for non-ohmic devices, this ratio changes with conditions.

Many components do not keep a constant (r). Their i–v relationship changes with operating conditions.

Diodes conduct strongly in one direction after a threshold-like region. Their resistance is not constant, so ohm’s law is not a simple straight-line relationship.

A filament lamp is considered non-ohmic because its resistance varies with temperature. As the filament heats up due to the electric current, its temperature increases, leading to an increase in resistance. This behavior deviates from Ohm's Law, which states that for a material to be ohmic, the current through it must be directly proportional to the voltage across it, with a constant resistance. In the case of a filament lamp, the changing resistance with temperature means that the relationship between voltage and current is not linear.

Slope in a v–i plot equals resistance. Larger slope corresponds to larger resistance.

If you plot (v) on the y-axis and (i) on the x-axis, slope is (v/i), which is (r). A steeper slope means higher resistance.