PHYS 203

Exam # 1

 

Name Date: August 19,1998

 

1. Draw equipotential lines through points A, B, and C for the field indicated below. Be sure to indicate which line has the highest potential by labeling the potentials 1, 2, and 3 with 3 being the highest potential. (8 Points)

 

 

 

 

 

2. A straight forward calculation: Determine the total resistance across terminals A and B for each diagram (8 Points)

 

 

 

3. Two plates having equal number of opposite charges are separated as shown with a hollow conducting box placed in between the plates. Draw a field line between the plates for each indicated charge including how the field interacts in and around the conducting box. (8 Points)

 

 

4. A charged pith ball having a mass of 1.3g is being held in equilibrium by an insulated string of length 0.35m at an angle of 120. The electric field is measured to have a strength of 8500N/C. Determine how much charge is on the pith ball and the sign of that charge. ( 8 Points)

 

 

5. A Hydrogen Ion is accelerated from a velocity of 5*104 m/s at plate A by a potential difference between plates A and B to attain a velocity of 4.5*105 m/s. Calculate the required potential on the plates given the mass of the Ion to be 3.34x10-27 kg. Label the potential on each plate. (10 Points)

 

 

 

 

6. A power conditioner utilizes a capacitor to provide extra energy on a booming car stereo. ( The bass notes require more energy.) In this system a bass note requires an extra 150W of power for 0.12 seconds at 12Vdc. What is the minimum value capacitor required to provide the extra energy? (8 Points)

 

 

 

 

 

 

 

 

 

 

7. The "Visible Resistor" is a conductive pendulum ball placed between two plates having a potential difference of 3200V. The ball oscillates between the plates and produces a current flow of 4.5*10-8A. The potential is increased to a value of 4350 volts and the current is now 5.1x10-8A. Determine if the "Visible Resistor" is a linear resistive device. ( 8 Points)

 

8. Two resistors having equivalent resistance are connected in series to a 6 volt battery. The current out of the battery is 10.3mA (9 Points)

a) What is the current through each resistor?

 

 

 

b) What is the voltage across each resistor?

 

 

 

c) What is the resistance of each resistor?

 

 

 

9. Two resistors of equivalent resistance are connected in parallel to a 6 volt battery. The current out of the battery is 10.3mA (9 Points)

a) What is the current through each resistor?

 

 

 

b) What is the voltage across each resistor?

 

 

 

c) What is the resistance of each resistor?

 

 

 

10. An electron is traveling with positive velocity v at point B. As it travels towards point C will the velocity increase or decrease. Justify your answer. (6 Points)

 

11. What is the magnitude and direction of the electric field at point O. (20 Points)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

12. What is the potential at point P (Q = 10mC)? ( 10 Points)

 

 

 

 

 

Use the physics principle you have learned the past few days and give short answers to these questions. (5 Points Each)

 

13.Why does a charged balloon attract your hair even though your hair is neutrally charged?

 

 

 

 

 

 

 

 

 

14. What is the peak value of the 120Vrms that comes form the wall outlet?

 

 

 

 

 

 

 

 

 

15. Can two equipotential lines cross each other? Explain.

 

 

 

 

 

 

 

 

 

16. Why do light bulbs tend to burn out when they are first turned on?