Exam 21: Alternating-Current Circuits and Electromagnetic Waves: Part A

A coil is placed in a magnetic field and has a flux Φ_B through it.The coil is stressed so that its area reduces to 60% of its original value.If the plane of the coil stays the same and the flux through it remains the same,how must the magnetic field change?

Which of the following is referred to as mutual inductance?

A large jetliner with a wingspan of 40 m flies horizontally and due north at a speed of 300 m/s in a region where the magnetic field of the earth is 51 µT directed 24.1° below the horizontal.What is the magnitude of the induced emf between the ends of the wing?

The first solenoid has 2 times the diameter,2 times the number of turns,and 2 times the length of the second solenoid.Which solenoid has the greater inductance and by what factor?

A 0.200-m wire is moved parallel to a 0.500-T magnetic field at a speed of 6.00 m/s.What emf is induced across the ends of the wire?

A square coil,enclosing an area with sides 3.0 cm long,is wrapped with 2500 turns of wire.A uniform magnetic field perpendicular to its plane is turned on and increases to 0.12 T during an interval of 1.0 s.What average voltage is induced in the coil?

The magnetic field inside a circular loop of wire of radius 30 cm increases at a constant rate from 2.0 × 10^-3 T to 3.5 × 10^-3 T in 0.47 s.What is the induced emf in the wire?

A loop of area 0.250 m² is in a uniform 0.0200-T magnetic field.If the flux through the loop is 3.21 × 10^-3 T·m²,what angle does the normal to the plane of the loop make with the direction of the magnetic field?

The self-inductance of a solenoid increases under which of the following conditions?

A changing current in one loop of wire can induce a current in another loop of wire even though the wires do not touch.The induced current appears almost instantaneously for loops close together.How can this energy exchange happen?

An RL circuit has L = 0.40 H and R = 5.0 Ω.It is connected to a battery with ε = 22 V at time t = 0.Find the energy stored in the inductor when the current in the circuit is 2.3 A.

What is the self-inductance in a coil that experiences a 3.0-V induced emf when the current is changing at a rate of 37 A/s?

The current in a coil with a self-inductance of 1.5 mH increases from 0 to 2.0 A in a tenth of a second.What is the induced emf in the coil?

An inductor has 1000 turns/m and an internal volume of 30 cm³.What is its inductance?

A coil in a magnetic field encloses a flux of 0.256 T·m² when the angle between the normal to the coil and the direction of the magnetic field is 70.0°.What flux would go through the coil if the angle were changed to 30.0°?

A coil with a self-inductance of 0.75 mH experiences a constant current buildup from zero to 15 A in 0.25 s.What is the induced emf during this interval?

A planar loop consisting of four turns of wire,each of which encloses 250 cm²,is oriented perpendicularly to a magnetic field that increases uniformly in magnitude from 10 mT to 25 mT in a time of 5.0 ms.What is the resulting induced current in the coil if the resistance of the coil is 5.0 Ω?

Three loops of wire,one circular,one rectangular,and one square,are made from identical lengths of wire.If the loops are in the same increasing magnetic field perpendicular to the plane of the coils,which loop has the least induced emf?

A 10-turn square coil of area 0.036 m² and a 6-turn circular coil are both placed at an angle of 25° to the same changing magnetic field.The voltage induced in each of the coils is the same.What is the area of the circular coil?

Two loops of wire are arranged so that a changing current in one,the primary,will induce a current in the other,the secondary.The secondary loop has twice as many turns as the primary loop.The current in the primary at this moment is 6 A and increasing.The current in the secondary must be: