# the strength of an electric field

What happens to the strength of an electric field when the charge on the test charge is halved? 6. What happens to the electric potential energy of a charged particle in an electric field when the particle is released and free to move? 7. A test charge experiences a force on . 30N on it when it is placed in an electric field intensity of 4. 5 x 10? N/C. What is the magnitude of the charge? Q= 6. 7 x 10-7C 8. What is the electric field strength 20. 0 cm from a point charge of 8. 0 x 10?? C? E=1. 8X105 N/C 9. How much work is done to transfer 0. 15C of charge through an electric potential difference of 9. V? W=1. 35J 10. A voltmeter measures the electric potential difference between two parallel plates to be 60. 0 V when the plates are separated by 3. 0 cm. What is the electric field strength between the plates? 11. Describe two ways to increase the current in a circuit. 12. Sue finds a device that look like a resistor. When she connects it to a 1. 5V battery, she measures only 45 x 10?? A, but when she uses a 3. 0 V battery, she measures 25 x 10?? A. Does the device obey Ohm’s law? NO 13. Refer to the diagram below to answer the following questions. a. What should the ammeter reading be? 1. 5 A b.

What should the voltmeter reading be? 27V c. How much power is delivered to the resistor? 40. 5 W d. How much energy is delivered to the resistor per hour? 1. 46×105 J/hr. 14. For each of the following write the form of circuit that applies: series or parallel. e. The current is the same everywhere throughout the entire circuit. f. The total resistance is equal to the sum of the individual resistance. g. The voltage drop across each resistor in the circuit is the same. h. The voltage drop in the circuit is proportional to the resistance. i. Adding a resistor to the circuit decreases the total resistance. j.

The voltage drop to the circuit increases the total resistance. k. If the current through one resistor in the circuit goes to zero, there is no current in the entire circuit. l. If the current through one resistor in the current goes to zero, the current through all the other resistors remains the same. m. This form is suitable for house wiring. 15. The load across a battery consists of two resistors with values of 15 ohms and 47 ohms, connected in series. n. What is the total resistance of the load? 62? o. What is the voltage of the battery if the current in the circuit is 97mA? 6. 0V 16. A 16. 0 ohm and a 20. ohm resistor are connected in parallel. A difference in potential of 40. 0 V is applied to the combination. p. Compute the equivalent resistance of the parallel circuit. 8. 9? q. What is the total current in the circuit? 4. 5V r. What is the current in the 16. 0ohm resistor? 2. 5 A 17. Describe how a permanent magnet differs from a temporary magnet. 18. A wire that is 0. 50m and carrying a current of 8. 0A is at a right angle to a uniform magnetic field. The force on the wire is . 40N. What is the strength of the magnetic field? B=0. 1 T 19. A beam of electrons moves at right angles to a magnetic field of 6. x 10?? T. The electrons have a velocity of 2. 5 x 10? m/s. What is the magnitude of the force on each electron? F=2. 4×10-14 N 20. An electric wire inside the wall of a building carries a dc current of 25 A vertically upward. What is the magnetic field due to this current at a point10 cm due north of the wire? B=5. 0x10-5T 21. Describe interference. Is interference a property of only some types of waves or all types of waves? 22. What happens to a spring at the nodes of standing waves? 23. Water waves in a lake travel 3. 4m in 1. 8s. The period of oscillation in 1. 1s. s.

What is the speed of the water waves? 1. 9m/s t. What is their wavelength? 2. 1m 24. The frequency of yellow lights is 5. 1 x 10?? Hz. Find the wavelength of yellow light. The speed of light is 3. 0 x 10? m/s. 5. 9×10-7 m 25. If the pitch of sound is increases, what are the changes in the following? u. the frequency v. the wavelength w. the wave velocity x. the amplitude of the wave 26. The sound from a trumpet travels at 351m/s in air. If the frequency of the note is 298Hz, what is the wavelength of the sound wave? 1. 18m 27. A ray of light strikes a mirror at an angle of 38° to the normal.

What is the angle that the reflected angle makes with the normal? 38o 28. A ray of light incident upon a mirror makes an angle of 36° with the mirror. What is the angle between the incident ray and the reflected ray? 108o 29. An object is placed 15 cm from a converging lens with a focal length of 10 cm. Determine the image location. Draw the ray diagram for this situation and describe the image. d i = 30. 0 cm 30. An object is 36. 0 cm in front of a concave mirror with a 16. 0 cm focal length. Determine the image position. Draw the ray diagram for this situation and describe the image d i = 28. 8cm