"Current and Circuits" Current and Circuits PPT (Lesson 1)

"Current and Circuits" Current and Circuits PPT (Lesson 1)

Part One Content: A Classification Practice of Knowledge Key Points

Knowledge point 1 Current

1. The ________ movement of charges forms an electric current; the charges that move in a directional manner may be ________ charges, or ________ charges, or they may be __________ moving in opposite directions at the same time.

2. We define the direction of directional movement of __________ as the direction of current, and the direction of directional movement of electrons is ______ with the direction of current. Outside the power supply, the current starts from the ________ pole of the power supply, passes through the electrical appliance, and returns to the ________ pole of the power supply.

3. As shown in Figure 15-2-1, the diode will emit light only when current flows in from its anode and flows out from its cathode. This shows that the diode has _______________ property.

Knowledge point 2: Circuit composition

4. A circuit is composed of four parts: ______, ________, ________ and ________. To have current in the circuit, there must be ______, and the circuit must be _______.

5. The electrical energy provided in the circuit is __________, and common batteries include __________ and __________. The casing (zinc skin) of a commonly used dry battery is its __________ pole, and the copper cap (connected to the carbon rod) is its __________ pole. The device that consumes electrical energy is __________, the device that delivers electrical energy is __________, and the device that controls the delivery of electrical energy is __________.

6. Regarding power supply, which of the following statements is incorrect ()

A. A power supply is a device that provides continuous electrical energy

B． As long as there is power in the circuit, there must be current

C. Convert other forms of energy into electrical energy when power is supplied

D． Generators are also power sources

7. Among the circuit components shown in Figure 15-2-2, the ones that do not belong to the same category as other components are ()

8. In the process of charging the mobile phone battery with a portable charger, the mobile phone battery is equivalent to () in the circuit

A. power supply

B． switch

C. wire

D． Electrical appliances

9. The condition for generating continuous current in a circuit is ()

A. There are electrical appliances in the circuit

B． There is power in the circuit

C. There is a switch in the circuit

D． There is power in the circuit and the circuit must be closed

Current and circuit PPT, part 2 content: Comprehensive practice of B-law method

11． Which of the following statements about electric current is correct ()

A. Only the directional movement of free electrons can form an electric current

B． As long as there is power in the circuit, there must be current

C. The direction of current in a circuit is from positive to negative

D． As long as there is directional movement of charges, an electric current can be formed

12. Regarding the direction of current, which of the following statements is correct ()

A. Negative charges move in the same direction as the current

B． Since positive and negative ions move in opposite directions at the same time, the direction of current in a conducting solution cannot be determined.

C. The direction of current in a metallic conductor is opposite to the direction in which the free electrons in it move

D． The direction in which charged particles move is the direction of current flow

13. (Multiple choice) As shown in Figure 15-2-4, when the switch S is closed and the small bulb L lights up normally, then ()

A. The direction of current passing through small bulb L is from b to c

B． The direction of free electron movement in the circuit is from a through b, c, d, e to f

C. The direction of free electron movement in the circuit is from f through e, d, c, b to a

D． The direction of current in the battery is from f to a

14. As shown in Figure 15-2-5A, electroscope A is negatively charged and electroscope B is uncharged. The moment when the two metal balls of electroscope A and B are connected with a metal rod with an insulated handle, as shown in Figure B, () in the metal rod

A. The positive charge in B flows through the metal rod to A,

A The opening angle of the metal foil decreases

B． The free electrons in A flow to B through the metal rod, and the opening angle of the metal foil B increases.

C. The negative charge in A flows to B through the metal rod, and the positive charge in B flows to A through the metal rod.

D． The direction of the instantaneous current in the metal rod flows from A to B, and the opening angle of the metal foil B increases.

15． There are two metal balls A and B. A is uncharged and B is positively charged. When the two metal balls A and B are connected with a wire, a short current flows through the wire. Regarding the direction of current and the cause of its formation, which of the following statements is correct ()

A. The direction of current is from B to A; the positive charge moves from B to A

B． The direction of current is from B to A; free electrons move from A to B

C. The direction of current is from A to B; free electrons move from A to B

D． The direction of current is from A to B; the positive charge moves from B to A

Current and circuit PPT, part 3 content: Practical practice of C high-frequency examination questions

18. [2017·Neijiang]As shown in Figure 15-2-7, it is a schematic diagram of the current generated by lightning passing through a lightning rod (it is known that the clouds are positively charged). Then the correct one of the following statements is ()

A. When lightning occurs, an electric charge is created

B． When lightning occurs, clouds lose their atomic nuclei

C. Clouds are positively charged because they have received electrons

D． The direction of the current in the picture is from the clouds to the lightning rod

19. [2017·Changde]As shown in Figure 15-2-8, there are two identical electroscopes A and B. A is positively charged and B is uncharged. Use a metal rod with an insulated handle to hold A Connected with B, which of the following statements is incorrect ()

A. A The opening angle of the metal foil becomes smaller, indicating that it obtains electrons

B． The opening angle of B metal foil becomes larger, indicating that the two metal foils carry the same charge.

C. Free electrons move directionally from B to A, forming an instantaneous current.

D． Positive charges move directionally from A to B, forming an instantaneous current.

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