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In the circuit, what are the burnt out appliances, ammeters and voltmeters equivalent to? Are they wires or switches?
Analysis: in circuit analysis, ammeter is equivalent to wire, voltmeter is equivalent to open circuit. Circuit connection must follow two principles: can not cause short circuit of the whole circuit, burn out the power or ammeter; at least one electrical appliance can work. According to the above requirements, put each option into the question to determine the correct answer
A if a, B and C are ammeters, closing the switch circuit will short circuit and the bulb will not light;
B
If a, B and C are all voltmeters, closing the switch circuit is equivalent to breaking the circuit, and the bulb is not on;
C
If B is an ammeter, a and C are both voltmeters, and the switch bulbs L1 and L2 are connected in series. The ratio of a and C is 1:3, and the voltage at both ends of the series circuit resistor is proportional to its resistance value, that is, the ratio of the two lamp resistors is 1:3. According to the formula P = UI, the ratio of the actual power of the two lamps is 1:3;
D
If B is a voltmeter, a and C are ammeters, close switch bulbs L1 and L2 in parallel. The ratio of a and C is 1:3, and the branch current of parallel circuit is inversely proportional to its resistance, that is, the ratio of filament resistance of two lamps is 3:1. According to the formula P = u2r, the ratio of actual power of two lamps is 1:3
So choose D
Comments: there are three steps to solve this problem: according to the position of ammeter and voltmeter to determine the circuit connection mode, according to the voltage and current relationship of series parallel circuit to get the size relationship of resistance, using the relationship between power and resistance of series parallel circuit to get the ratio relationship of actual power consumed by two lamps
The resistance of a section of conductor is 6 Ω, and the current passing through it is 0.5 A. what is the voltage at both ends of the conductor at this time?
According to Ohm's law I = u / R
U = I * r = 0.5A * 6 Ω = 3V
So the voltage at both ends of the conductor is 3V
RELATED INFORMATIONS
- 1. The resistance of an electric lamp is 10 ohm. The normal operation is that the voltage at both ends of the lamp should be 5 V, but the current power supply around us is 8 v How much resistance does it need to connect in series to make the lamp work normally?
- 2. When an unknown resistance is connected to the power supply in series with a 6 Ω resistance, its voltage at both ends is 4V; when it is connected to the same power supply in series with a 9 Ω resistance, its voltage at both ends is 3V
- 3. After a 3V, 15W small bulb is connected in series with a 2 ohm resistor, the small bulb lights up normally Seek 1: resistance R of small bulb 2: Voltage across resistor R2 3: If the small bulb is directly connected to the power supply, the small bulb will not be burnt out
- 4. As shown in the figure, the power supply voltage is 9V and remains unchanged, the range of the ammeter is 0 ~ 0.6A, and the resistance of the small bulb is 9 Ω, in order not to let the current in the circuit exceed the electric current What is the minimum value of sliding resistor in the circuit?
- 5. 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?
- 6. 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
- 7. When a wire passes the current of 0.5A for 10s, the amount of charge passing through the wire is
- 8. 4V battery with 100 Ω resistance in parallel, the voltage is only 3.9v, what's the reason? Is it related to the current?
- 9. 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
- 10. 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?
- 11. An ammeter is equivalent to a wire. What is a voltmeter equivalent to?
- 12. How to judge which electric appliance or circuit is measured by Voltmeter and ammeter
- 13. In refitting the ammeter, wouldn't it be short circuited by connecting a resistor to the ammeter
- 14. Connect wires on both sides of the resistance, and the resistance is short circuited. It can be seen that the resistance is in parallel with that wire. Because the resistance of the wire is small, the current is low So is the current basically distributed to the wire? In fact, will there be a little current through the short-circuit resistor?
- 15. Physics and electricity in Junior Three
- 16. Electricity. It's very easy, that is, when there is a short circuit, does the voltmeter show the number and ammeter? Is it open circuit?
- 17. Short circuit / open circuit, is there current or voltage? When the circuit is short circuited, When the circuit is short circuited, When the circuit is open, When the circuit is open, Please give a specific answer So why is there current and no voltage when there is a short circuit? Is voltage not the cause of travel current? How can there be current without voltage?
- 18. There is a section of conductor. When the voltage at both ends is 2 V, the current passing through it is 0.5 A, and the resistance of this section of conductor is () A. if the applied voltage is zero, the current passing through it is () a, and the resistance of this section of conductor is () Ω
- 19. Give you a battery pack, two switches S1 and S2, two lights L1 and L2, and several wires. Design a circuit. Requirements: when S1 is closed only, L1 and L2 will light up; when S2 is closed only, L1 and L2 will not light up; when S1 and S2 are closed, L2 will not light up, L1 will light up, and it is bright
- 20. As shown in the figure, the circuit only needs to change the connection of one wire, so that the ammeter can measure the current passing through two bulbs at the same time, mark "×" on the wire to be connected, and then draw the wire to be connected