Ch 29-31 Review

1. A closed loop moves at a constant speed perpendicular to a long straight current-carrying wire, as shown. Which of the following is true?

• The induced current is clockwise.

• There is no induced current.

• The induced current is counterclockwise.

• The induced current is clockwise, then counterclockwise.

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

2. A magnetic field has a magnitude field of 54 mT and makes an angle of 37° with the +z-axis. What is the flux through a square 25 cm on each side lying in the xy-plane?

• 2.6 mWb

• 26 Wb

• 2.0 mWb

• 11 mWb

3. An electric motor, under load, has an effective resistance of 30 Ω and an inductive reactance of

40 Ω. When powered by an 120 V AC source with frequency 60 Hz, the average power

dissipated is:

• 288 W

• 120 W

• 1170 W

• 173 W

Tags

NGSS.HS-PS3-5

4. The resonant frequency of an RLC circuit with a 20 Ω resistor, 35 mH inductor, and 40 µF capacitor is:

• 845 Hz

• 6.7 Hz

• 134 Hz

• 2157 Hz

5. The bar magnet shown in the figure at right is moved completely through the loop. Which of the following is a true statement about the direction of the current flow between the two points a and b in the circuit?

• No current flows between a and b as the magnet passes through the loop.

• Current flows from a to b as the magnet passes through the loop.

• Current flows from b to a as the magnet passes through the loop.

• Current flows from a to b as the magnet enters the loop and from b to a as the magnet leaves the loop.

• Current flows from b to a as the magnet enters the loop and from a to b as the magnet leaves the loop.

Tags

NGSS.HS-PS2-5

6. A planar EM wave is propagating in the +x direction. At P, 𝐸 = (0.082 V/m) 𝚥̂. What is the magnetic vector of the wave at the point P at that instant?

• 0.27 nT 𝚥̂

• 0.27 nT k̂

• -0.27 nT k̂

• 6.8 nT k̂

• -6.8 nT 𝚥̂

Tags

NGSS.HS-PS2-5

7. An alternating EMF has the form V = (30 V) sin (250t). If it is connected in series with a 305 mH inductor, a 75 μF capacitor, and a 15 Ω resistor, the current is given by:

• i = (30 A) sin (250t)

• i = (1.1 A) sin (250t + 0.99

• i = (1.1 A) sin (250t – 0.99)

• i = (0.17 A) sin(250 + π/2)

• i = (0.17 A) sin (250t + 1.4)

Tags

NGSS.HS-PS4-1

8. Which of the following gives the correct phasor diagram for the voltage across each of the elements in

problem 7?

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Tags

NGSS.HS-PS4-1

9. The capacitor in Circuit 1 above left is charged. If switch S is closed at time t = 0, which of the following represents the magnetic energy, U, in the inductor as a function of time? (Assume that the capacitor and inductor are ideal.)

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Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-2

10. In the Circuit 2 above right, Vi is the amplitude of the input voltage and Vo is the amplitude of the output voltage. If the angular frequency ω of the input voltage is varied, which of the following gives the ratio Vo /Vi = G as a function of ω?

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Tags

NGSS.HS-PS4-1