Ch 22 HW: Problem 22.1 - Motional EMF
A conducting rod oriented horizontally along an east-west axis has a length 2.4 meters and is
dropped from some height. As it falls, it reaches a downward velocity of 35 m/s at a given
instant. The rod falls through a uniform magnetic field generated by the Earth of 57 µT directed
38° vertically downward from true horizontal North.
a)
b)
c)
Determine the magnitude of the EMF induced between the ends of the rod.
Which end of the rod is positive, east or west? Draw a diagram to help justify your answer.
If a current were to flow through this rod in response to the voltage difference, in what
direction would the magnetic force on the rod point?
Ch 22 HW: Problem 22.2 - Magnetic Flux and Induction
A rectangular loop of length ( ) 35.0 cm, width (w) 22.0 cm and resistance 0.150 Ω moves at a
constant speed of 12.0 cm/s in the +x direction as shown below. The loop has 125 turns, and it
moves into a region of uniform magnetic field pointing into the page with a magnitude of 8.50
Tesla. When the loop is entering the magnetic field region and halfway immersed in the field,
determine
(a) the induced EMF in the loop,
(b) the direction of induced current and
(c) the magnitude and direction of the magnetic force acting on the loop as a result of the
induced current.
(d) Also describe what happens to each of your answers to (a), (b) and (c) once the loop is fully
immersed in the uniform magnetic field.
Ch 22 HW: Problem 22.3 - Magnetic Flux and Induction
A solenoid has 240 turns/cm and a radius of 1.5 cm. It carries an initial constant current of 1.5
Amps in the clockwise direction when seen end-on (cutaway on left, end-on view on right). The
solenoid is coaxial with a coil of wire of radius 1.8 cm, 350 turns and a total resistance of 2.7 Ω.
If the current in the solenoid drops from 1.5 A to zero in a time interval of 0.025 seconds,
what is the magnitude and direction (seen end-on) of the induced current in the coil?
b) If the current in the solenoid starts at zero and increases to 1.5 A in a counterclockwise
direction in 0.025 seconds, what is the magnitude and direction of induced current in the
coil?
a)
Ch 22 HW: Problem 22.4 - Generators
The 1250-turn wire coil below has a radius of 22.5 cm, a resistance of 0.560 Ω, and rotates
through a uniform 5.50 Tesla magnetic field in such a way that the top half of the coil comes out
of the page and the bottom half of the coil goes into the page.
a) If the coil completes exactly one quarter turn
in 0.120 seconds, what is the magnitude
and direction of the average induced current
in the coil during that interval?
b) Suppose this is a generator. What is its
angular frequency, ω?
c) What is the rms value of the current
produced by this generator?
Ch 22 HW: Problem 22.5 - Transformers
A step-down transformer is used for recharging portable batteries. The turns ratio for a
particular transformer is 10:1, with the primary coil of the transformer being connected to the
household circuit (with rms value of 120 Volts) and the secondary coil connected to the
rechargeable battery, which draws an rms current of 0.150 Amps.
a) What is the rms output voltage of the secondary coil of the transformer?
b) What is the power delivered to the rechargeable battery by the secondary coil?
c) An extension cord with a resistance of 0.240 Ω connects the household plug socket to the
transformer for the rechargeable battery. What is the average power dissipated by the
extension cord?