Ven, 14/11/2014 - 13:35
red - Di seguito vengono proposti alcuni esercizi di Fisica in lingua Inglese, inerenti alla corrente elettrica. Tali esercizi possono essere utilizzati nelle classi quinte in cui sono stati attivati dei percorsi CLIL di Fisica in lingua Inglese.
- What is the current in milliamperes produced by the solar cells of a pocket calculator through which 4.00 C of charge passes in 4.00 h?
- A total of 600 C of charge passes through a flashlight in 0.500 h. What is the average current?
- large lightning bolt had a 20,000-A current and moved 30.0 C of charge. What was its duration?
- The 200-A current through a spark plug moves 0.300 mC of charge. How long does the spark last?
- (a) A defibrillator sends a 6.00-A current through the chest of a patient by applying a 10,000-V potential as in the figure below. What is the resistance of the path? (b) The defibrillator paddles make contact with the patient through a conducting gel that greatly reduces the path resistance. Discuss the difficulties that would ensue if a larger voltage were used to produce the same current through the patient, but with the path having perhaps 50 times the resistance. (Hint: The current must be about the same, so a higher voltage would imply greater power. Use this equation for power: P = I2R.)
- During open-heart surgery, a defibrillator can be used to bring a patient out of cardiac arrest. The resistance of the path is 500 Ω and a 10.0-mA current is needed. What voltage should be applied?
- A clock battery wears out after moving 10,000 C of charge through the clock at a rate of 0.500 mA. (a) How long did the clock run? (b) How many electrons per second flowed?
- What is the effective resistance of a car’s starter motor when 150 A flows through it as the car battery applies 11.0 V to the motor?
- The diameter of 0-gauge copper wire is 8.252 mm. Find the resistance of a 1.00-km length of such wire used for power transmission.
- A copper wire has a resistance of 0.500 Ω at 20.0°C, and an iron wire has a resistance of 0.525 Ω at the same temperature. At what temperature are their resistances equal?
- A piece of steel wire has a resistence of 10 Ω. It is stretched to twice its original length. Compareits new resistance to its original resistance.
- When a potential diﬀerence of 1.5 V is applied across a 5.0 m length of insulated copper wire, acurrent of 0.24 A passes through it. Calculate the resistance of the length of wire. The resistivity of copper is 1,69 · 10-8 Ω·m, calculate the diameter of the wire.
- Explain why the resistance of a metallic conductor increases with temperature whereas that of a semiconductor decreases.