"Laws of Current in Series and Parallel Circuits" Current and Circuit PPT

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"Laws of Current in Series and Parallel Circuits" Current and Circuit PPT

Part One Content: A Classification Practice of Knowledge Key Points

Knowledge point 1: Explore the laws of current in series circuits

1. When exploring the "laws of current in series circuits", the students drew the circuit diagram shown in Figure 15-5-1. The experimental process was as follows:

(1) Conjecture: As shown in Figure 15-5-2, water flows at a constant speed in the water pipe, and the water flow rate through three points a, b, and c is the same within the same time. Compare the wire to a water pipe and the current to water flow, so the current passing through points A, B, and C ________.

(2) When conducting experiments and connecting circuits, the switch should ________.

(3) Turn off the switch, connect ________ to A, B, and C respectively, and measure the current passing through the three points. The measurement data is as shown in the table below.

2. As shown in Figure 15-5-3, AB and CD are two sections of metal conductors with the same length and different thicknesses made of the same material. They are connected in series and connected to the circuit. If the currents flowing through conductors AB and CD are I1 respectively and I2, then()

A. I1>I2

B． I1

C. I1=I2

D． unconfirmed

3. In the circuit shown in Figure 15-5-4, close the switch and measure the current at point b with an ammeter to be 1.8 A. Then the current at point a is ________ and the current at point c is ________.

Knowledge point 2: Explore the laws of current in parallel circuits

4. When the students were exploring the "laws of current in parallel circuits", they drew the circuit diagram shown in Figure 15-5-5. The experimental process was as follows:

(1) Conjecture: As shown in Figure 15-5-6, water flows at a constant speed in the water pipe. The sum of the water flow rates passing through points a and b in the same time period is equal to the water flow rate passing through point c. Compare the wire to a water pipe and the current to water flow, so the current passing through point C is equal to the current passing through points A and B _________.

(2) Connect the circuit and conduct experiments. Due to limited time, the students only measured one set of data, as shown in the table below.

(3) According to the above data, it can be concluded that the main circuit current in the parallel circuit is equal to the current of each branch ________.

(4) Please analyze the shortcomings of the experimental plan and write down methods for improving the experiment.

(4) Answer

Improvement method: Replace the two light bulbs with light bulbs of different specifications, conduct several more experiments, and measure several different sets of data to summarize the experimental conclusions.

5. Three identical light bulbs L1, L2, and L3 form the circuit shown in Figure 15-5-7. When the switch is closed, the readings of the ammeters A1, A2, and A3 are I1, I2, and I3 respectively. The relationship between them is ()

A. I1=I2

B． I3＝I2＋I1

C. I1＝I2＋I3

D． I2=I3

The law of current in series and parallel circuits PPT, the second part of the content: Comprehensive practice of the B law method

6. Student Jingjing connected two light bulbs with different specifications in series to the same power supply. One bulb emits a strong light, while the other bulb emits a darker light. The students talked about it. What do you think is correct? ( )

A. Strong light bulbs have large currents

B． The current in a dim light bulb is small

C. The current in both bulbs is the same

D． Light bulbs that glow dimly may have poor contact

7. The following are some statements about the current laws in series and parallel circuits that Xiao Ming has explored. Which one do you think is incorrect ()

A. The current in a series circuit is equal everywhere

B． In a parallel circuit, the trunk current is equal to the sum of the branch currents.

C. If the current through two light bulbs is equal, the two light bulbs must be connected in series.

D． The current in a branch of a parallel circuit is equal to the main circuit current minus the current in other branches

8. As shown in Figure 15-5-8, lamps L1 and L2 are connected in series in the circuit. Xiao Ming wants to use an ammeter to measure the current in the series circuit. He connects the ammeter between points B and C. What will happen after closing the switch is: ()

A. Lamps L1 and L2 are not on, and the ammeter has no indication.

B． Lamps L1 and L2 are both on, but the ammeter has no indication.

C. L1 is on, L2 is off, and the ammeter shows a reading.

D． L1 is off, L2 is on, and the ammeter shows a reading.

9. In the physical circuit shown in Figure 15-5-9, when the switch is closed, the reading of ammeter A is 0.5 A, and the reading of ammeter B is 0.2 A, then the following judgment is correct ()

A. The current through lamp L1 is 0.5 A

B． The current through lamp L1 is 0.3 A

C. The current through lamp L2 is 0.7 A

D． The current through lamp L2 is 0.3 A

10. In the circuit shown in Figure 15-5-10A, when the switch S is closed, the pointer of the ammeter deflects as shown in Figure B, in which the ammeter a measures the voltage through ________ (optional "power supply" "L1" or "L2" ) current, b The indication of the ammeter should be ________A, and the current through L2 is ________A.

11． In the circuit shown in Figure 15-5-11, after switch S is closed, the pointers of ammeters A and A1 deflect at the same angle, then the ratio of the currents passing through bulbs L1 and L2 is ________.

12. Figure 15-5-12A shows the experimental circuit diagram used by Xiaojuan to explore the "current law of series circuits". Figure B shows the experimental equipment provided.

(1) In the experiment, the specifications of the two small bulbs selected should be ________ (please fill in "the same" or "different").

(2) Please help Xiaojuan connect to the physical diagram in Figure B (use an ammeter to measure the current at point a). When you connect the circuit, the switch should ______. After connecting the physical diagram, check the circuit.

(3) During the experiment, after Xiaojuan closed the switch, she found that among the small light bulbs connected in series, L1 emits strong light and L2 does not emit light. The reason why L2 does not emit light may be ()

A. L2 short circuit B. L2 filament is broken

C. The switch is open D. L1 short circuit

The law of current in series and parallel circuits PPT, the third part of the content: Practical practice of C high-frequency examination questions

13. [2016·Changchun]In the circuit shown in Figure 15-5-13A, when the switch is closed, both bulbs light up, and the pointers of two identical ammeters deflect as shown in Figure B, then The currents passing through bulbs L1 and L2 are () respectively

A. 1.2A　1.2A

B． 0.3A　0.3A

C. 1.2A　0.3A

D． 1.5A　0.3A

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Update Time: 2024-11-20

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