The electric field in a cathode ray tube is supposed to accelerate electrons from 0 to 3.2 107 m/s in a distance of 2.00 cm. What electric field is required? (me = 9.11 1031 kg and e = 1.60 1019 C)
a. 4.6E+4 N/C
b. 2.3E+5 N/C
c. 1.5E+5 N/C
d. 2.9E+5 N/C
e. 1.6E+4 N/C
[Ques. 2] An engineer designed a transformer to convert 120 V (rms) to 6.0 V (rms). The number of turns in the primary is 540, and the secondary current is 610 mA at an output voltage of 6.0 V (rms). What is the current in the primary?
a. 30.5 mA
b. 4.50 mA
c. 32.8 mA
d. 136 mA
[Ques. 3] Electrons in a particle beam each have a kinetic energy of 4.0 1017 J. What is the magnitude of the electric field that will stop these electrons in a distance of 0.3 m? (e = 1.6 1019 C)
a. 1.9E+3 N/C
b. 7.5E+3 N/C
c. 8.3E+2 N/C
d. 1.3E+3 N/C
e. 6.3E+3 N/C
[Ques. 4] An engineer designed a transformer to convert 120 V (rms) to 6.0 V (rms). The number of turns in the primary is 540, and the secondary current is 610 mA at an output voltage of 6.0 V (rms). How many turns are in the secondary?
a. 90
b. 27
c. 5
d. 3 240
[Ques. 5] An airplane is flying through a thundercloud at a height of 2 500 m. (This is a very dangerous thing to do because of updrafts, turbulence, and the possibility of electric discharge.) If there is a charge concentration of +42 C at height 4 000 m within the cloud and 42 C at height 500 m, what is the magnitude of the electric field E at the aircraft? (ke = 8.99 109 Nm2/C2)
a. 9.4E+4 N/C
b. 1.7E+5 N/C
c. 6.2E+4 N/C
d. 2.6E+5 N/C
e. 1.9E+5 N/C
[Ques. 6] Transmitting power at high voltage, e.g., 400,000 V, reduces the power loss for transmission lines. But such a voltage would destroy electrical devices in household use. How then can such 400,000 V electricity be used in a normal house?
a. The ground prongs on household plugs reduce the voltage to 120 V.
b. Before reaching households, transformers are used to reduce the voltage appropriately.
c. No matter the incoming voltage, a 120-V device only lets 120 V in.
d. The 400,000 V is just theoretical; long distance transmission lines actually use 120 V.
[Ques. 7] In x-ray machines, electrons are subjected to electric fields as great as 6.0 105 N/C. Find an electron's acceleration in this field. (me = 9.11 1031 kg, e = 1.6 1019 C)
a. 1.1E+17 m/s2
b. 3.4E+13 m/s2
c. 8.7E+10 m/s2
d. 2.9E+8 m/s2
e. 4.1E+13 m/s2
[Ques. 8] An ideal transformer is one that:
a. has a turn ratio, N2/N1, equal to 1.
b. works with direct current.
c. experiences no power loss.
d. has an output frequency of 60 Hz.
[Ques. 9] An electron with a speed of 2.0 106 m/s moves into a uniform electric field of 550 N/C that is parallel to the electron's motion. How long does it take to bring the electron to rest? (me = 9.11 1031 kg, e = 1.6 1019 C)
a. 2.1E8 s
b. 6.4E9 s
c. 1.6E6 s
d. 1.6E6 s
e. 3.1E7 s
[Ques. 10] The primary winding of an electric train transformer has 445 turns, and the secondary has 300 . If the input voltage is 118 V(rms), what is the output voltage?
a. 175 V
b. 53.6 V
c. 79.6 V
d. 144 V
e. 118 V
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