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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?
In the circuit, the current I = u lamp / R lamp = 5V / 10 Ω = 0.5A
Resistor sharing voltage ur = U-U lamp = 8v-5v = 3V
Resistance value of series resistance R = ur / I = 3V / 0.5A = 6 Ω
When the voltage at both ends of a fixed value resistor is 4 V, the current passing through it is 0.5 A. if the voltage at both ends of the resistor increases to 5 V, can the current with the range of 0.6 a be used
Ammeter to measure the current through the resistance
No, because the resistance value r = u / I = 4 / 0.5 = 8 ohm, the current I = u / r = 5 / 8 = 0.625 at 5V has exceeded
There is a small light bulb. When it works normally, the resistance is 10 Ω and the voltage is 4V. There is only a 6V power supply and several 10 Ω resistors on hand. How can it work normally?
The normal working voltage of the small bulb is 4V, while the power supply voltage is 6V. Therefore, the method of series voltage division can be used to make the small bulb work normally. According to the principle of series voltage division, 4 / 10 = (6-4) / R, r = 5ohm, so the 5ohm resistance can be obtained by paralleling two 10ohm resistors, and then it can be connected in series with the small bulb
When an electric bell works normally, its resistance is 10 ohm, and its voltage is 4V, but there is only a 6V power supply and several 10 ohm resistors on hand
How to make the bell work normally? Try to answer by calculation
First of all, the current of the bell is 4V / 10 Ω = 0.4A
With 6V voltage on hand, the total resistance of the circuit is 6V / 0.4A = 15 Ω
If two 10 Ω resistors are connected in parallel, the resistance of the parallel circuit is 5 Ω
If it is connected in series with the bell, the total resistance is 15 Ω
RELATED INFORMATIONS
- 1. 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
- 2. 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
- 3. 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?
- 4. 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?
- 5. 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
- 6. When a wire passes the current of 0.5A for 10s, the amount of charge passing through the wire is
- 7. 4V battery with 100 Ω resistance in parallel, the voltage is only 3.9v, what's the reason? Is it related to the current?
- 8. 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
- 9. 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?
- 10. 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)
- 11. In the circuit, what are the burnt out appliances, ammeters and voltmeters equivalent to? Are they wires or switches?
- 12. An ammeter is equivalent to a wire. What is a voltmeter equivalent to?
- 13. How to judge which electric appliance or circuit is measured by Voltmeter and ammeter
- 14. In refitting the ammeter, wouldn't it be short circuited by connecting a resistor to the ammeter
- 15. 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?
- 16. Physics and electricity in Junior Three
- 17. 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?
- 18. 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?
- 19. 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
- 20. 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