True-false questions are worth 2 points each, three-choice multiple choice questions are worth 3 points each, five-choice multiple choice questions are worth 6 points each. The maximum possible score is 131. The exam period was 90 minutes; the mean score was 96.9; the median was 98. Click here to see page1 page2 page3 of the formula sheet that came with the exam.

Some helpful information: • A reminder about prefixes: p (pico) = 10^{-12}; n (nano) = 10^{-9}; μ (micro) = 10^{-6}; m (milli) = 10^{-3}; k (kilo) = 10^{+3}; M or Meg (mega) = 10^{+6}; G or Gig (giga) = 10^{+9}.

A positively charged particle in a uniform external magnetic field moves in a circular path in the clockwise direction, parallel to the plane of the page. In what direction do the magnetic field lines point?

(a) out of the page (b) into the page (c) to the left (d) to the right (e) in a clockwise pattern parallel to the plane of the page

I. Maximize the strength of the magnetic field II. Minimize the particle's velocity III. Ensure that the particle is moving in the same direction as the magnetic field lines

(a) I only (b) I and II only (c) I and III only (d) II and III only (e) I, II, and III

(a) (b) (c) (d) (e)

At what velocity v must the particle be moving if it is not deflected when it enters this area?

(a) v = 4.0 × 10^{-3} m/s (b) v = 125 m/s (c) v = 250 m/s (d) v = 500 m/s (e) The particle will be deflected to the left regardless of its velocity.

(a) It is quartered. (b) It is halved. (c) It is unchanged. (d) It is doubled. (e) It is quadrupled.

Which one of the graphs at right represents the magnetic force acting on each wire?

At which point is the total magnetic field the strongest?

(a) A (b) B (c) C (d) D (e) The total magnetic field strength is uniform throughout.

What is the induced emf ε in the bar and rails?

(a) ε = 2 × 10^{-5 }V (b) ε = 2 × 10^{-4} V (c) ε = 4 × 10^{-4} V (d) ε = 2 × 10^{-3} V (e) ε = 4 × 10^{-3} V

What is the magnitude and direction of the current I_{2} in the bottom wire?

(a) I_{2} = 7.5 A to the left (b) I_{2} = 7.5 A to the right (c) I_{2} = 0 A (d) I_{2} = 16.5 A to the left (e) I_{2} = 16.5 A to the right

A 4 cm × 3 cm rectangular loop is made of a wire with resistance per unit length of 25 Ohm/m. The loop is placed in a region of uniform magnetic field, B = 5 T. The direction of B is perpendicular to the plane of the loop and points into the page as shown.

The magnetic field starts to increase at a uniform rate of 0.1 T/sec. What is the magnitude of the induced current in the loop?

(a) I = 0 A (b) I = 3.4 × 10^{-5} A (c) I = 1.2 × 10^{-4} A (d) I = 0.02 A (e) I = 4.8 A

(a) counterclockwise (b) clockwise (c) There is no induced current.

Which picture best describes the EMF generated in the loop as a function of position of the ring?

(a) (b) (c)

(a) magnet A (b) magnet B (c) They hit at the same time.

A mechanical crank is used to turn a rectangular loop with area 0.33 m^{2} at angular frequency ω in the presence of a magnetic field B = 0.8 T as shown. The 200 V peak EMF produced in the loop results in a peak voltage across the primary of the transformer of V_{p} = 200 V. The secondary windings are connected to an oscilloscope, and the peak voltage is 100 volts.

If the primary coil has 100 windings, how many windings are there in the secondary coil? (Note number of windings on picture is not accurate!)

(a) N_{s} = 50 (b) N_{s} = 100 (c) N_{s} = 200

(a) T = 2.3 ms (b) T = 3.6 ms (c) T = 4.1 ms (d) T = 8.3 ms (e) T = 9.8 ms

The solenoid shown below has length l = 0.15 m and cross-sectional area A = 3.5 × 10^{-4} m^{2}. Its self-inductance is L = 25 mH. A current I of 2.5 amps flows through its coils in the direction shown in the figure.

Which way does the magnetic field point inside the solenoid?

(a) to the left (b) to the right

(a) U_{m} = 78 mJ (b) U_{m} = 123 mJ (c) U_{m} = 175 mJ (d) U_{m} = 208 mJ (e) U_{m} = 345 mJ

(a) B = 14 mT (b) B = 36 mT (c) B = 48 mT (d) B = 61 mT (e) B = 88 mT

A single-turn rectangular wire loop of size 20 cm × 30 cm rotates at a uniform rate of ω = 50 rad/sec around the z-axis as shown. There is a uniform magnetic field B in the +y-direction. The loop has a total resistance of R = 36 Ω.

At the instant shown, an induced current in the loop will

(a) flow clockwise. (b) flow counterclockwise. (c) not flow.

(a) B = 0.17 T (b) B = 0.29 T (c) B = 0.55 T (d) B = 0.68 T (e) B = 0.79 T

The phasor diagram below yields information on a particular series RLC circuit. It is only partially labeled, but you should know from examining it the proper quantity that is referred to by each number, given in ohms, in the drawing.

What is the total impedance, Z, of the circuit?

(a) Z = 12 Ω (b) Z = 18 Ω (c) Z = 36 Ω (d) Z = 40 Ω (e) Z = 65 Ω

(a) C = 0.21 μF (b) C = 0.59 μF (c) C = 3.17 μF (d) C = 17.6 μF (e) C = 33.3 μF

(a) increased. (b) decreased. (c) left as is, since the circuit is already in resonance.

In the following RLC circuit, E(t) is given in volts and time is in seconds.

What is the phase angle Φ by which the voltage leads the current?

(a) Φ = +73.8° (b) Φ = +37.6° (c) Φ = 0 (d) Φ = -37.6° (e) Φ = -73.8°

(a) the inductor (b) the capacitor (c) the resistor

In the drawing below, you are looking at an edge view of a single turn rectangular wire loop, which is being rotated clockwise. There is a uniform magnetic field B which points to the right. The three drawings show the position of the coil at three different times.

For which drawing is the magnitude of the magnetic flux through the loop the largest?

(a) the left drawing (b) the center drawing (c) the right drawing