Why is resistivity constant for a material?

Resistivity depends on the temperature of the material. At a constant temperature, we can assume the resistivity is a constant, and use Ohm’s Law which states that the resistance will be constant. This assumes the the current is not so large that it would heat up the material significantly.

What is resistance in a material?

Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current.

Why do different materials have different resistance?

The resistance of a given wire depends upon its cross-sectional area and its length. One wire that has twice the diameter of another wire has four times the cross-sectional area of the smaller wire. Conversely, the longer the wire is, the more resistance the electrons encounter.

How does material affect resistance?

The thicker the wire, the lower the resistance. (3) Material: the material the wire is made out of will affect the resistance. Different materials have different resistivities, which is the ability of the material to allow electrons to move. It is dependent on electronic structure and temperature.

Is the resistance constant?

In order for a material to obey Ohm’s law the resistance must remain constant – meaning that the current and potential difference must be proportional to each other. = potential difference (measured in volts) R. = the circuit resistance (measured in ohms) – which remains constant in order to obey Ohm’s law.

What is constant resistance or resistivity?

Resistivity, commonly symbolized by the Greek letter rho, ρ, is quantitatively equal to the resistance R of a specimen such as a wire, multiplied by its cross-sectional area A, and divided by its length l; ρ = RA/l. The unit of resistance is the ohm.

Do all materials have resistance?

All materials have some resistance, but certain materials resist the flow of electric current more or less than other materials do. Materials such as plastics have high resistance to electric current. Materials such as metals have low resistance to electric current. They are called electric conductors.

What causes resistance in a metal?

As electrons move through a metal conductor, some collide with atoms, other electrons or impurities. Heating the metal conductor causes atoms to vibrate more, which in turn makes it more difficult for the electrons to flow, increasing resistance.

What are the factors on which resistance of a material depends on?

The resistance of the conductor depends on the following factors:

• The temperature of the conductor.
• The cross-sectional area of the conductor.
• Length of the conductor.
• Nature of the material of the conductor.

What are the four factors that affect the resistance of a material?

There are 4 different factors which affect resistance:

• The type of material of which the resistor is made.
• The length of the resistor.
• The thickness of the resistor.
• The temperature of the conductor.

What are the causes of resistance?

Resistance is caused in a conductor by the free electrons. These free electrons collide with each other and with the ions and atoms that oppose their free movement. This obstruction is known as resistance.

Why does the resistance do not remain constant when voltage increases?

Answer: Ohm’s law states that the electrical current (I) flowing in an circuit is proportional to the voltage (V) and inversely proportional to the resistance (R). Therefore, if the voltage is increased, the current will increase provided the resistance of the circuit does not change.