(II) Inductive battery chargers, which allow transfer of electrical power without the need for exposed electrical contacts, are commonly used in appliances that need to be safely immersed in water, such as electric toothbrushes. Consider the following simple model for the power transfer in an inductive charger (Fig. 29–42). Within the charger’s plastic base, a primary coil of diameter d with n P turns per unit length is connected to a home’s ac wall outlet so that a current I = I 0 sin ( 2 π f t ) flows within it. When the toothbrush is seated on the base, an N -turn secondary coil inside the toothbrush has a diameter only slightly greater than d and is centered on the primary. Find an expression for the emf induced in the secondary coil. [This induced emf recharges the battery.]
(II) Inductive battery chargers, which allow transfer of electrical power without the need for exposed electrical contacts, are commonly used in appliances that need to be safely immersed in water, such as electric toothbrushes. Consider the following simple model for the power transfer in an inductive charger (Fig. 29–42). Within the charger’s plastic base, a primary coil of diameter d with n P turns per unit length is connected to a home’s ac wall outlet so that a current I = I 0 sin ( 2 π f t ) flows within it. When the toothbrush is seated on the base, an N -turn secondary coil inside the toothbrush has a diameter only slightly greater than d and is centered on the primary. Find an expression for the emf induced in the secondary coil. [This induced emf recharges the battery.]
(II) Inductive battery chargers, which allow transfer of electrical power without the need for exposed electrical contacts, are commonly used in appliances that need to be safely immersed in water, such as electric toothbrushes. Consider the following simple model for the power transfer in an inductive charger (Fig. 29–42). Within the charger’s plastic base, a primary coil of diameter d with nP turns per unit length is connected to a home’s ac wall outlet so that a current
I
=
I
0
sin
(
2
π
f
t
)
flows within it. When the toothbrush is seated on the base, an N-turn secondary coil inside the toothbrush has a diameter only slightly greater than d and is centered on the primary. Find an expression for the emf induced in the secondary coil. [This induced emf recharges the battery.]
(II) How many time constants does it take for thepotential difference across the resistor in an LR circuit likethat in Fig. 21–37 to drop to 2.5% of its original value, afterthe switch is moved to the upper position, removing fromthe circuit?
(II) A heater coil connected to a 240Vrms ac line has aresistance of 38 Ω (a) What is the average power used?(b) What are the maximum and minimum values of theinstantaneous power?
(I) At what frequency will a 2.40μF capacitor have a reactance of 6.10 KΩ ?
Chapter 29 Solutions
Physics for Scientists and Engineers with Modern Physics
Essential University Physics: Volume 2 (3rd Edition)
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What is Electromagnetic Induction? | Faraday's Laws and Lenz Law | iKen | iKen Edu | iKen App; Author: Iken Edu;https://www.youtube.com/watch?v=3HyORmBip-w;License: Standard YouTube License, CC-BY