Why do some materials heat up faster with current?

Some materials heat up faster with current due to their higher electrical resistivity, which leads to more heat generation.

In more detail, the heating effect of an electric current is a phenomenon where electrical energy is converted into heat energy. This is known as Joule heating or resistive heating. The amount of heat produced is directly proportional to the square of the current (I^2), the resistance (R), and the time (t) the current flows, as given by Joule's first law: H = I^2Rt.

Materials with higher electrical resistivity heat up faster because they oppose the flow of electric current more than materials with lower resistivity. This opposition to current flow results in more energy being dissipated as heat. For example, metals like copper and aluminium have low resistivity and are good conductors of electricity, so they don't heat up as quickly. On the other hand, materials like tungsten and nichrome have high resistivity and heat up faster when current is passed through them.

The heating effect of current is utilised in many everyday appliances. For instance, in an electric kettle, the heating element is made of a high-resistivity material. When electric current passes through the element, it heats up quickly and transfers this heat to the water to boil it. Similarly, in an incandescent light bulb, the filament is made of tungsten. The high resistivity of tungsten causes it to heat up and glow brightly when current is passed through it.

In summary, the rate at which a material heats up with current is determined by its electrical resistivity. The higher the resistivity, the more the material opposes the flow of current, and the more heat is generated. This principle is fundamental to the operation of many electrical appliances and systems.