Question

1. which of the following determines the amount of current produced in a conductor by a changing magnetic field? (13.1)

(a) the rate of change of the magnetic field
(b) the strength of the magnetic field
(c) coiling the conductor
(d) all of the above

1. which of the following materials would work best for a pot used on an induction cooker? (13.1)

(a) aluminum
(b) glass
(c) iron
(d) plastic

1. a metal detector relies on an induced current in the metal to be detected. why is the induced current necessary? (13.1)

(a) the induced current creates a magnetic field that is detected.
(b) the induced current is directly detected by an ammeter in the metal detector.
(c) the induced current creates a vibration due to the moving electrons that is detected.
which angles relative to the magnetic field? (11.4)
(a) 0° and 180°
(b) 45° and 135°
(c) 90° and 270°
(d) 90° and 180°

1. which of the following transformer ratios, \\(\frac{n_p}{n_s}\\), will produce the most current in the secondary circuit? (13.5)

(a) \\(\frac{2}{5}\\)
(b) \\(\frac{3}{7}\\)
(c) \\(\frac{6}{5}\\)
(d) \\(\frac{9}{4}\\)

1. for a given amount of power and transmission line resistance, at which of the following voltages should a power plant transmit electricity in order to minimize the amount of power lost? (13.6)

(a) 20 v
(b) 12 kv
(c) 250 kv

Explanation:

Question 1

To determine the amount of current from a changing magnetic field (electromagnetic induction), Faraday's law states induced emf (and thus current) depends on the rate of change of magnetic flux. The rate of change of the magnetic field affects flux change. The strength of the magnetic field also impacts flux (more strength, more flux change if area/rate is constant). Coiling the conductor increases the number of loops, increasing induced emf (and current) by Faraday's law (\( \mathcal{E} = -N\frac{\Delta \Phi}{\Delta t} \)). So all factors (rate of change, field strength, coiling) affect the current.

Induction cookers work via electromagnetic induction, requiring a ferromagnetic material to induce eddy currents (for heating). Iron is ferromagnetic, so it will have strong eddy currents. Aluminum is non - ferromagnetic (weak response), glass and plastic are non - conductive/non - magnetic, so no eddy currents.

Answer:

(d) all of the above

Question 2