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ConcepTest 26.3b Wires II

"When a wire of resistance R is stretched uniformly to double its length while keeping its volume constant, the resistance increases by a factor of four."

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ConcepTest 26.3b Wires II

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  1. ConcepTest 26.3b Wires II 1) it decreasesby a factor 4 2) it decreasesby a factor 2 3) it stays the same 4) it increasesby a factor 2 5) it increasesby a factor 4 A wire of resistance R is stretched uniformly (keeping its volume constant) until it is twice its original length. What happens to the resistance?

  2. ConcepTest 26.3b Wires II 1) it decreasesby a factor 4 2) it decreasesby a factor 2 3) it stays the same 4) it increasesby a factor 2 5) it increasesby a factor 4 A wire of resistance R is stretched uniformly (keeping its volume constant) until it is twice its original length. What happens to the resistance? Keeping the volume (= area x length) constant means that if the length is doubled, the area is halved. Since , this increases the resistance by four.

  3. 9 V ConcepTest 26.4a Series Resistors I 1)12 V 2)zero 3)3 V 4) 4 V 5) you need to know the actual value of R Assume that the voltage of the battery is 9 V and that the three resistors are identical. What is the potential difference across each resistor?

  4. 9 V ConcepTest 26.4a Series Resistors I 1)12 V 2)zero 3)3 V 4) 4 V 5) you need to know the actual value of R Assume that the voltage of the battery is 9 V and that the three resistors are identical. What is the potential difference across each resistor? Since the resistors are all equal, the voltage will drop evenly across the 3 resistors, with 1/3 of 9 V across each one. So we get a 3 V drop across each. Follow-up: What would be the potential difference if R= 1 W, 2 W, 3 W

  5. ConcepTest 26.6b Short Circuit II 1) glow brighter than before 2) glow just the same as before 3) glow dimmer than before 4) go out completely 5) explode Two lightbulbs A and B are connected in series to a constant voltage source. When a wire is connected across B, bulb A will:

  6. ConcepTest 26.6b Short Circuit II 1) glow brighter than before 2) glow just the same as before 3) glow dimmer than before 4) go out completely 5) explode Two lightbulbs A and B are connected in series to a constant voltage source. When a wire is connected across B, bulb A will: Since bulb B is bypassed by the wire, the total resistance of the circuit decreases. This means that the current through bulb A increases. Follow-up: What happens to bulb B?

  7. R1 S R3 V R2 ConcepTest 26.8aMore Circuits I 1) increase 2) decrease 3) stay the same What happens to the voltage across the resistor R1 when the switch is closed? The voltage will:

  8. R1 S R3 V R2 ConcepTest 26.8aMore Circuits I 1) increase 2) decrease 3) stay the same What happens to the voltage across the resistor R1 when the switch is closed? The voltage will: With the switch closed, the addition of R2 to R3decreases the equivalent resistance, so the current from the battery increases. This will cause an increase in the voltage across R1 . Follow-up:What happens to the current through R3?

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