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Adjustable Light "Resistor" Course Presentation

  The adjustable resistor changes the current in the circuitObserve the adjustable resistor carefully. Examine the physical object on the tabletop and study its structure and the functions of each component.

Think about the patterns: for connecting circuits, how should adjustable resistors be connected? For the adjustable brightness small light, do you know how the brightness of the bulb is controlled? During a performance in a theater, we observe that the lights gradually darken and then gradually brighten. Now there are two bulbs connected to the circuit. How can we change their brightness?

Resistance change, current change – thought: What methods can be used to alter the resistance of a conductor?

Which method is simpler? What methods can be used to change the magnitude of the current?

Principle: Changing the number of turns in the adjustable resistor in the circuit to alter the resistance in the circuit.

Principle of the sliding rheostat:

The resistance is changed by altering the length of the resistance wire in the connection circuit.

How to use the sliding rheostat:

The resistance wire of the sliding rheostat is not connected to the circuit, so it cannot change the resistance and thereby alter the current. This is an incorrect usage.

Similar to a fixed resistance in the circuit, it also cannot change the resistance, and thus cannot alter the current.

Experimental Report

The resistance ring becomes longer, the resistance increases, the current decreases, and the light becomes dimmer.

The resistance ring becomes shorter, the resistance decreases, the current increases, and the light becomes brighter.

Explore: What patterns can be found among the connection methods of varistors?

The series connection is discussed in the circuit, regarding the large current that can pass through when dealing with high resistance values.