(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?
If magnetic coils are powered by AC, why don’t their contacts open and close 120 times per second?
(III) In Fig. 21–11, the rod moves with a speed of 1.16 m/s onrails 30.0 cm apart. The rod has a resistance of 2.5Ω Themagnetic field is 0.35 T, and the resistance of theconductor is 21.0Ω at a given instant. Calculate (a) theinduced emf, (b) the current in the conductor,and (c) the external force needed to keep the rod’s velocityconstant at that instant.
Chapter 29 Solutions
Physics for Scientists & Engineers with Modern Physics [With Access Code]
Essential University Physics: Volume 2 (3rd Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.
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