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Why can't we screw copper and aluminum wires together to connect the lines
When the air is wet, it is an electrolyte. When the copper wire and aluminum wire are screwed together to connect the circuit, the chemical reaction between the two metals will corrode one of the less active metals. To put it simply, when the copper wire and aluminum wire are screwed together to connect the circuit, the aluminum wire will corrode and oxidize when it comes into contact with the air, which will damage the circuit
Why can't we screw copper wire and aluminum wire together to connect the circuit
Copper and aluminum can form galvanic cell under certain conditions, which makes chemical reaction between the two metals, resulting in poor contact and even open circuit
In a circuit, why can a switch be regarded as a wire when it is connected with a resistor in parallel and closed?
Because parallel current has two ways to go, but because the resistance is difficult to go (you can be a man), and the switch resistance is smaller, so the current will not go the resistance that way, only go the switch! This is often used in later exercises! So it can be seen as a wire!
RELATED INFORMATIONS
- 1. It is known that the circuit has two fixed value resistors, a switch and a 60V power supply connected by wires. And the power supply voltage is constant. When the switch is in a certain state (open or closed), the electric power of the circuit is 40W. When the switch is in another state, the electric power of the circuit is increased by 20W. The resistance values of the two fixed value resistors are calculated
- 2. When a resistance is increased by 3 Ω, the current in the circuit becomes four fifths of the original value. If the supply voltage remains unchanged, what is the original value of the resistance?
- 3. How to change resistance, current and voltage in series / parallel circuit? The sliding rheostat changes the resistance in the circuit. How do the current and voltage at both ends of the planting resistor change? How do the total voltage and current change?
- 4. How to change resistance current and voltage with sliding rheostat in series circuit? How to change resistance current and voltage with sliding rheostat in parallel circuit
- 5. How does the change of resistance of sliding rheostat affect the change of voltage This is the eighth edition of Zhejiang Education Press. May I ask why the voltage of sliding rheostat in the circuit (series or parallel) changes? Why does the resistance of constant value resistor not change but affect the voltage? Does sliding rheostat affect the current, resistance and voltage? Another question: which factors are related to the brightness of the bulb? Current, voltage or resistance? There must be a lot of additional points!
- 6. If the voltage U and the resistance R are doubled simultaneously in a circuit, how will the power change? P = the square of (2U) divided by 2R Why is the square of (2R) divided by R
- 7. In the experiment of exploring the relationship between current and voltage, resistance, when exploring the relationship between current and resistance, we should () A. Adjust the sliding rheostat to keep the current in the circuit constant B. Adjust the sliding rheostat so that the voltage at both ends of different fixed resistor R remains unchanged C. Make the voltage at both ends of resistance R change in multiple D. The current in the circuit should be changed in multiple during each measurement
- 8. In the experiment of studying the relationship between current, voltage and resistance, what is used to control the current in the circuit
- 9. Is the statement "when the resistance of a conductor is constant, the current is proportional to the voltage"? Those who are right should pay attention! I thought it was right, but the answer is wrong! I wonder if it should be said that when the resistance of a conductor is constant, the current in the conductor is proportional to the voltage at both ends of the conductor! I want to win your opinions,
- 10. The resistance of a conductor is directly proportional to the voltage at both ends of the conductor and inversely proportional to the current passing through the conductor Why wrong? How to understand the relationship between resistance, voltage and current? Don't use books. It's suitable for multiple choice questions
- 11. How to prevent oxidation of wire joint, copper wire and aluminum wire joint
- 12. (1) If the wire connection in the home circuit is not in good contact, it will often heat there and cause danger. Why 2. Xiao Li bought two incandescent bulbs, one marked with "20V 100W" and the other marked with "220V 15W". Can you judge which bulb to compete with 3. In order to save electricity, Xiao Hui wants to use two "220V 15W" light bulbs in series, and then connect them to the 220 V home circuit, and use them as aisle lights. Do you think this method is feasible? Can two light bulbs replace one light bulb really save electricity? Calculate the actual electric power of each light bulb in series 4. The working resistance of a refrigerator in Xiao Li's home is 20 ohm, and the working current is 0.5A. Can you estimate the electric power of this refrigerator
- 13. When 3V voltage is applied at both ends of a conductor, the current passing through the conductor is 0.2A, and the resistance of the conductor is______ When a voltage of 6V is applied at both ends of the conductor, the resistance of the conductor is equal to______ Ω．
- 14. In the circuit as shown in the figure, the power supply voltage is 6V constant, the range of ammeter is 0-0.6a, the range of voltmeter is 0-3v, the lamp L1 and The specifications of L2 are "6V, 1.8W" and "6V, 1.2W" respectively. The specifications of sliding rheostat are "50ohm, 1.5A". Only close S1S2 to find the range of ammeter and voltmeter (the safety of components in the circuit)
- 15. In the experiment of exploring the relationship between current and resistance, the slide of sliding rheostat is adjusted to keep the voltage at both ends of the resistance unchanged. If the voltage does not change, does not the current also change? Does not the calculated resistance also change?
- 16. When the voltage at both ends of a resistor increases from 2V to 2.8V, the current through the resistor increases by 0.1A, then the resistance value of the resistor is () A. 8 Ω B. 20 Ω C. 28 Ω D. cannot be determined
- 17. 4V battery with 100 Ω resistance in parallel, the voltage is only 3.9v, what's the reason? Is it related to the current?
- 18. When a wire passes the current of 0.5A for 10s, the amount of charge passing through the wire is
- 19. In the circuit shown in the figure, the resistance value of resistor R1 is 5 ohm, the current indication is 0.6A, and the voltage at both ends of resistor R2 is 2.5V Find the retention of & lt; 1 & gt; R1, the current of & lt; 2 & gt; R2, the resistance of R2, and the total resistance of & lt; 3 & gt; circuit
- 20. When 18V voltage is applied to a certain section of conductor, the current passing through it is 0.6A, then the resistance to the body is () ohm. If 9V voltage is applied to this section of conductor, the current passing through the conductor?