PHYSICS 220BL #85506 FALL 2000

FINAL EXAMINATION

NAME_______________

Part I (50%)

Answer the following questions:

You need to answer the questions in detail, and give the necessary support statements.

  1. State the correct way to use the voltmeter.
  2. How can you tell a battery is used up?
  3. What precautions do you take in the Wheastone-Bridge Experiment? How can you get a more accurate result in this experiment?
  4. What is the most uncertain measurement in determining the charge-to-mass ratio of electrons?
  5. An AC power supply has variable frequency adjustment. When we connect a pure resistor of 1.2kW across the power supply at 5V, what is the current in the circuit? We connect the same resistor, an inductor and a capacitor in series with the AC power supply at 5V. If we measure the current as 3mA at resonance, what is the resistance of the inductor?
  6. How do we use the oscilloscope to measure the phase angle in an RC circuit?
  7. A step-up transformer has turn ratio of 5:1. If the current in the primary coil is 3A and the voltage in the secondary coil is 24V, what is the power of the transformer. Assume that the transformer is an ideal one.
  8. We calculate a physical quantity using the relevant quantities, which are measured experimentally. If we can measure this quantity directly in the experiment, which result do you trust better, experimental one or calculated one? Give an example to defend your statement.
  9. What is the difference between an ammeter and a galvanometer? How do you use an ammeter?
  10. Why is it important to keep the black paper clean during the procedure of plotting equipotential lines?

 

Part II (50%)

Project:

There are a standard resistor, an inductor with known inductance and an unknown capacitor. Design an experiment to find the accurate value of the capacitance of the capacitor using the given resistor and inductor. You need to state the apparatus, the procedure, circuits, and the relevant calculations.

How do you use your experimental results to find the resonance frequency of the RLC series circuit, which consists of the given resistor, inductor and the capacitor?