"Series and Parallel Connections of Resistors" Exploring Circuit PPT Courseware 2

Description

"Series and Parallel Connections of Resistors" Exploring Circuit PPT Courseware 2

life and physics

If your Walkman stops ringing, check and find that a 200 ohm resistor is burned out and needs to be replaced. But you only have a few 400 ohm and a few 100 ohm resistors on hand. Can you combine them so that the combined resistance is equivalent to a 200 ohm resistor?

Experimental exploration: series and parallel connections of resistors

(1) When resistors are connected in series, will the total resistance increase or decrease?

(2) When resistors are connected in parallel, will the total resistance increase or decrease?

Discussion and exchange

Use a voltmeter to measure the total voltage across the series resistors R1 and R2, and then use an ammeter to measure the current through the resistor. Then you can calculate the total resistance of R1 and R2 in series according to Ohm's law, so you can compare the total resistance and the divided resistance of the series circuit. Resistor size relationship.

Use a voltmeter to measure the voltage across the parallel resistors R1 and R2, and then use an ammeter to measure the main circuit current. Then you can calculate the total resistance of R1 and R2 in parallel according to Ohm's law, so you can compare the total resistance and partial resistance of the parallel circuit. size relationship.

Give it a try

After connecting the circuit according to the circuit diagram, close the switch, observe the indications of the ammeter and voltmeter, record the data, and then calculate the total resistance R of the series and parallel connection according to Ohm's law.

get conclusion

When resistors are connected in series, the total resistance is greater than the resistance of any individual resistor.

Theoretical derivation:

According to Ohm's law:

U1 = I R1, U2= I R2, U = I R

Since U = U1 + U2,

Therefore IR = IR1 + IR2,

So R = R1 + R2.

Conclusion: The total resistance of a series circuit is equal to the sum of the individual series resistances.

Experimental results:

When resistors are connected in parallel, the total resistance is smaller than the resistance of any individual resistor.

Theoretical derivation:

According to Ohm's law:

I1 = U/ R1, I2 = U/ R2, I = U/ R,

Since: I = I1 + I2,

Therefore: U/R = U/R1+ U/R2.

Obtain: 1/R = 1/ R1 + 1 / R2.

Conclusion: The reciprocal of the total resistance of a parallel circuit is equal to the sum of the reciprocals of the parallel resistances.

Communication and discussion 1:

The above conclusion about series resistance is derived from two series resistances. Is it suitable for situations where 3, 4, or multiple resistors are connected in series?

Communication and discussion 2:

When two identical resistors are connected in parallel, what is the total resistance based on the relationship between the parallel resistors? What is the total resistance when three or more resistors are connected in parallel?

From physics to life

If your Walkman stops ringing, check and find that a 200 ohm resistor is burned out and needs to be replaced. But you only have a few 400 ohm and a few 100 ohm resistors on hand. Can you combine them so that the combined resistance is equivalent to a 200 ohm resistor?

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For more information about the PPT courseware "Exploring the Series and Parallel Connections of Circuit Resistors", please click the Explore the Series and Parallel Connections of Circuit Resistors PPT tag.

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Update Time: 2024-10-03

This template belongs to Physics courseware Shanghai Science Edition Ninth Grade Physics industry PPT template

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