Conductors, resistors and insulators

The idea

For components of the same size, one with low resistance is a good conductor, one with appreciable resistance is a resistor, one with higher resistance is a poor conductor, and an insulator has even higher resistance.

Four rods

Four rods of the same size are made of different materials. They are joined to the same cell, one at a time. The current is different for each rod.

Which rod will let the smallest current flow?

• The one with the highest resistance, the insulator
• The one with the lowest resistance, the good conductor
• All four let the same current flow

Match them

Tap a description on the left, then the name on the right that goes with it.

A ladder of resistance

For components of the same size, the lower the resistance, the better the conductor. As the resistance grows we go from a good conductor to a resistor, then to a poor conductor, and last to an insulator.

For components of the same size, one with low resistance is a good conductor, one with appreciable resistance is a resistor, one with higher resistance is a poor conductor, and an insulator has even higher resistance.

Notes

For components of the same size: low resistance is a good conductor, appreciable resistance a resistor, higher resistance a poor conductor, and an insulator has even higher resistance.

Check yourself

For components of the same size, which one has the highest resistance?

What is a conductor having some appreciable resistance called?

Two components of the same size are joined to the same cell, one at a time. One is a good conductor and the other is a poor conductor. Which carries the larger current?

• The insulator — correct. Yes!
• The good conductor. A good conductor offers a low resistance.
• The resistor. A resistor has some appreciable resistance, but a poor conductor and an insulator offer higher resistance.
• A good conductor. A good conductor offers a low resistance.
• A resistor — correct. Yes!
• An insulator. An insulator offers even higher resistance than a poor conductor.
• The poor conductor. A poor conductor offers a higher resistance, so for the same potential difference its current is smaller.
• They carry the same current. Their resistances are different, so by I = V/R the currents are different.
• The good conductor — correct. Yes!