Exam 29: Electromagnetic Induction

A coil is in a perpendicular magnetic field that is time dependent and given by B = 0.600 - 3.7t T.If the induced voltage around the coil is 7.4 V,what is its area in m²?

A loop of wire lies motionless on a flat,horizontal surface in the presence of a uniform and constant magnetic field.When is the magnetic flux through the area interior to the loop the largest?

An elastic circular conducting loop expands at a constant rate in time.The radius is initially 0.200 m,but then begins to increase 0.018 m every second.The loop has a constant resistance of and is placed in a region of uniform (same everywhere)magnetic field of 0.880 T,perpendicular to the plane of the loop.Calculate the resistance of the loop if magnitude of the induced current 2.4 s after the loop begins expanding is 1.3 * 10^-3 A)

The conducting loop in the shape of a quarter-circle has a radius of 10 cm and resistance of 0.2 ohms.The magnetic field strength within the dotted circle of 3-cm radius is initially 2 T.If the magnetic field strength decreases from 2 T to 1 T in 2 s,find the magnitude and the direction of the induced current in the loop.

The magnetic field in the coil is upward and increasing.The direction of the induced current in the coil,as viewed from the top is

An emf of 10 V is applied to a coil with an inductance of 40 mH and a resistance of 0.50 $\varOmega$ .Determine the energy stored in the magnetic field when the current reaches one half of its maximum value.

A conducting rod is pulled horizontally with constant force F = 5.00 N along a set of rails separated by d = 0.56 m.A uniform magnetic field B= 0.60 T is directed into the page.There is no friction between the rod and the rails,and the rod moves with constant velocity v = 4.00 m/s.Using Faraday's Law,calculate the magnitude of the induced emf (in V)around the loop in the figure that is caused by the changing flux.

A 10-turn square loop (0.250 m along a side,resistance = 4.00 $\varOmega$ )is placed in a magnetic field that makes an angle $\alpha$ with the normal to the plane of the loop.The magnitude of this field varies with time according to B = 2.70t²,where t is measured in s and B in T.The induced current in the coil at t = 1.50 s is 0.750 A. The angle $\alpha$ made by the magnetic field with the plane of the loop is

An emf of 10 V is applied to a coil having an inductance of 40 mH resistance of .If it takes 0.55 s for the current to reach one half of its maximum value,what is the resistance of the coil?

A wire loop of radius 10 cm has a resistance of 2.0 $\varOmega$ .The loop is at right angles to a uniform magnetic field B. The field strength is changing at a rate of $\Delta$ B/ $\Delta$ t = 0.10 T/s.What is the magnitude of the induced current in the loop?

Electrons are circulating in a 0.58 m diameter cyclotron orbit in a uniform magnetic field of 1.1 T.One can think of these circulating electrons as a circular current loop with the same diameter.The magnetic field is then rapidly increased at a constant rate.If the magnitude of the induced electric field causing the electrons to increase their speed 25 ms after the magnetic field begins increasing is 0.73 V/m,what is rate at which the field is increasing? This is the basis for accelerating electrons in a betatron.

An emf of 10 V is applied to a coil with an inductance of 40 mH and a resistance of 5.0 .Determine the energy stored in the magnetic field when the current reaches its maximum value.

An LR circuit is hooked up to a battery as shown in the figure,with the switch initially open.The resistance in the circuit is R = 11.0,the inductance is L = 3.00 H,and the battery maintains a voltage of E = 36.0 V.At time t = 0 the switch is closed.How much time (in seconds)does it take until the voltage across the resistor is equal to the voltage across the inductor?

The figure shows the current through a 10-mH inductor.What is maximum magnitude of the potential difference $\Delta$ V_L across the inductor over the period shown?

Electrons are circulating in a 0.58 m diameter cyclotron orbit in a uniform magnetic field of 1.1 T.One can think of these circulating electrons as a circular current loop with the same diameter.The magnetic field is then rapidly increased at a constant rate of 2.5 T/s.What is the magnitude of the induced electric field causing the electrons to increase their speed 25 ms after the magnetic field begins increasing? This is the basis for accelerating electrons in a betatron.

A single rectangular wire loop with a height of 24.0 cm and a width of 10.0 cm is mounted flat on an office door.The resistance of the loop is 3.85 $\varOmega$ .The Earth's magnetic field of 2.6 * 10^-5 T is uniform and perpendicular to the surface of the closed door.The door is then opened at a constant rate of 4.6 rad/s.Calculate the magnitude of the induced current 0.434 s after the door begins opening.

A solenoid has N = 490 loops of wire and a cross-sectional area A = 15 cm².It is moved from a field-free region to one where the magnetic field B = 0.8 T points directly along the axis of the solenoid.If the motion proceeds with constant velocity and takes t = 15 seconds,what is the magnitude of the average induced EMF?

A 2.0 m long solenoid of cross sectional area 1.4 m² and n=300 turns/m carries a current of 4.0 A.What is the energy stored in the solenoid?

The figure shows the current through an inductor.If the maximum magnitude of the potential difference $\Delta$ V_L across the inductor over the period shown is 60 V,what is the inductance of the inductor?

A loop of wire sits in the plane of the page you are looking at,and the magnetic field in which the loop is sitting comes out of the page and is increasing in strength with time according to B = B₀t².What properly describes the current induced in the loop?