p117b_07_t3_ans

P117b_07_t3_ans - 1 Alpha particles(charge = 2e mass = 6.68 x 10-27 kg are accelerated in a cyclotron to a final orbit radius of m The magnetic

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Unformatted text preview: 1) Alpha particles (charge = +2e, mass = 6.68 x 10-27 kg) are accelerated in a cyclotron to a final orbit radius of ) m. The magnetic field in the cyclotron is ) T. The kinetic energy of an alpha particle in the final orbit is closest to: A) ) MeV B) ) MeV C) ) MeV D) ) MeV E) ) MeV Answer: A 2) If you were to cut a small permanent bar magnet in half, A) one piece would be a magnetic north pole and the other piece would be a south pole. B) neither piece would be magnetic. C) each piece would in itself be a smaller bar magnet with both north and south poles. D) each piece would contain both north and south poles, but on a given piece the intensity of the north and south poles would not necessarily be equal. E) None of these statements is true. Answer: C 3) Which of the following is an accurate statement? A) A current carrying loop of wire tends to line up with its plane parallel to an external magnetic field in which it is positioned B) A magnetic field line is, by definition, tangent to the direction of the magnetic force on a moving charge at a given point in space. C) The magnetic force on a moving charge does not change its energy. D) The magnetic force on a current carrying wire is greatest when the wire is parallel to the magnetic field. E) None of these Answer: C In this figure, a uniform magnetic field of magnitude 0.80 T in the negative z-direction is present in a region of space. A uniform electric field is also present. 4) In the above figure, an electron, projected with an initial velocity V0 = ) x 104 m/s in the positive xdirection, traverses the region without deflection. The electric field vector, in kV/m, is closest to: A) - ) j B) + ) i C) + ) i D) + ) j E) - ) j Answer: A 5) In the figure above, a wire segment 1.2 m long carries a current I = 3.5 A, and is oriented as shown. A uniform magnetic field of magnitude 0.50 T is present as shown. Right-handed coordinates are used (as standard, +z is into the page). The magnetic force on the wire segment, in SI units, is closest to: A) +1.6 j B) -1.6 k C) +1.6 k D) +1.8 j - 1.6 k E) -1.8 j + 1.6 k Answer: C Figure 27.8 A rigid circular loop has a radius of 0.20 m and is in the x-y plane. A clockwise current I is carried by the loop, as shown. The magnitude of the magnetic moment of the loop is 0.75 Am2. A uniform external magnetic field, B = 0.20 T in the positive x-direction, is present. 6) In the above figure, the current in the loop is closest to: A) 3.0 A B) 4.5 A C) 6.0 A D) 7.5 A E) 9.0 A Answer: C 7) In the figure above, the magnitude of the magnetic torque exerted on the loop is closest to: A) 0.15 N m B) 0.25 N m C) 0.35 N m D) 0.45 N m E) 0.55 N m Answer: A 8) A point charge Q moves on the x-axis in the positive direction with a speed of ) m/s. A field point is on the y-axis at y = + ) mm. The magnetic field produced at the field point, as the charge moves through the origin, is equal to ) mT pointing in negative z direction. The charge Q is closest to: A) - ) mC B) + ) mC C) - ) mC D) + ) mC E) + ) mC Answer: A 9) A circular loop of radius 10 cm and three long straight wires carry currents of I1 = ) A, I2 = ) A, I3 = ) A, and I4 = ) A, respectively, as shown. Each straight wire is 20 cm from the center of the loop. In Figure 28.1, the y-component of the resultant magnetic field at the center of the loop is closest to: A) - ) µ T B) - ) µ T C) - ) µ T D) + ) µ T E) + ) µ T Answer: A 10) A solenoid shown above, is wound with ) turns on a form 4 cm in diameter and 50 cm long. The windings carry a current in the sense that is shown. The current produces a magnetic field, of magnitude ) mT, at the center of the solenoid. In Figure 28.7, the current in the solenoid windings is closest to: A) ) A B) ) A C) ) A D) ) A E) ) A Answer: A 11) In the figure above, a wire and a 10 ohm resistor are used to form a circuit in the shape of a square, 20 cm by 20 cm. A uniform but non-steady magnetic field is directed into the plane of the circuit. The magnitude of the magnetic field is decreased from ) T to ) T in a time interval of ) ms. The average induced current and its direction through the resistor, in this time interval, are closest to: A) ) mA, from b to a B) ) mA, from b to a C) ) mA, from a to b D) ) mA, from a to b E) ) mA, from a to b Answer: A 12) In the figure above, a coil of wire is placed on the axis of a solenoid carrying a DC current. Which of the following will NOT result in an EMF being induced in the coil? A) Rotate the coil about the x-axis. B) Rotate the coil about the y-axis. C) Rotate the coil about the z-axis. D) Move the coil toward point P. E) Change the current in the solenoid. Answer: C 13) In the figure above, the inner loop carries a current I that is increasing. The resistor R is in the outer loop. The induced current through the resistor R is: A) zero B) from a to b C) from b to a Answer: B 60V )H )Ω 14) An R-L circuit shown above, has a 60 V battery, a ) H inductor, a ) ohm resistor, and a switch S, in series, as shown. Initially, the switch is open, and there is no magnetic flux in the inductor. At time t = 0 s, the switch is closed. In Figure 30.1a, when the time t = ) s, the current in the circuit is closest to: A) ) A B) ) A C) ) A D) ) A E) ) A Answer: A A non-planar rigid loop shown above, has two vertical sections, numbered 1 and 3, which are 20 cm long. It also has two 90 degree arc sections, numbered 2 and 4. The curved sections have a radius of 8 cm, and the centers are on the z-axis. The loop carries a current of 15 A, as shown. A straight wire lies on the zaxis and carries a current of 25 A, as shown. 15) The force exerted on section 1 due to the 25 A current is closest to: A) zero B) (+2 x 10 -4 N) i C) (-2 x 10 -4 N) j D) (-4 x 10 -4 N) i E) (+4 x 10 -4 N) j Answer: C 16) In the figure above, the force exerted on section 2 due to the 25 A current is closest to: A) zero B) (+1.2 x 10 -4 N) i C) (-1.2 x 10 -4 N) j D) (+1.7 x 10 -5 N) i + (1.7 x 10 -5 N) j E) (+1.7 x 10 -5 N) i - (1.7 x 10 -5 N) j Answer: A ...
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This document was uploaded on 09/05/2011.

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