Exam 23: Faradays Law and Inductance

A rectangular wire loop (length = 60 cm,width = 40 cm)lies completely within a perpendicular and uniform magnetic field of magnitude of 0.5 T.If the length of the loop starts increasing at a rate of 20 mm/s at time t = 0,while the width is decreasing at the same rate,what is the magnitude of the induced emf at time t = 4.0 s?

An induced emf is produced in

A metal blade (length = 80 cm)spins at a constant rate of 10 radians/s about a pivot at one end.A uniform magnetic field of 2.0 mT is directed at an angle of 30 $\degree$ with the plane of the rotation.What is the magnitude of the potential difference between the two ends of the blade?

Starting outside the region with the magnetic field,a single square coil of wire enters,moves across,and then leaves the region with a uniform magnetic field $\vec { B }$ perpendicular to the page so that the graph shown below represents the induced emf.The loop moves at constant velocity $\overrightarrow { \mathbf { v } }$ .As seen from above,a counterclockwise emf is regarded as positive.In which direction did the loop move over the plane of the page?

A 20-cm length of wire is held along an east-west direction and moved horizontally to the north with a speed of 3.0 m/s in a region where the magnetic field of the earth is 60 $\mu$ T directed 30 $\degree$ below the horizontal.What is the magnitude of the potential difference between the ends of the wire?

A conducting bar moves as shown near a long wire carrying a constant 80-A current.If a = 1.0 mm,b = 20 mm,and v = 5.0 m/s,what is the potential difference,V_a - V_b?

Coil 1,connected to a 100 $\Omega$ resistor,sits inside coil 2.Coil 1 is connected to a source of 60 cycle per second AC current.Which statement about coil 2 is correct?

A square loop (length along one side = 20 cm)rotates in a constant magnetic field which has a magnitude of 2.0 T.At an instant when the angle between the field and the normal to the plane of the loop is equal to 20 $\degree$ and increasing at the rate of 10 $\degree$ /s,what is the magnitude of the induced emf in the loop?

In a demonstration,a 4.00 cm² square coil with 10 000 turns enters a larger square region with a uniform 1.50 T magnetic field at a speed of 100 m/s.The plane of the coil is perpendicular to the field lines.If the breakdown voltage of air is 4 000 V/cm on that day,the largest gap you can have between the two wires connected to the ends of the coil and still get a spark is

A current may be induced in a coil by

A long solenoid has a radius of 2.0 cm and has 700 turns/m.If the current in the solenoid is decreasing at the rate of 8.0 A/s,what is the magnitude of the induced electric field at a point 2.5 cm from the axis of the solenoid?

A 50-turn circular coil (radius = 15 cm)with a total resistance of 4.0 $\Omega$ is placed in a uniform magnetic field directed perpendicularly to the plane of the coil.The magnitude of this field varies with time according to B = A sin ( $\alpha$ t),where A = 80 $\mu$ T and $\alpha$ = 50 $\pi$ rad/s.What is the magnitude of the current induced in the coil at t = 20 ms?

A conducting bar of length L rotates with a constant angular speed of +2.0 rad/s about a pivot P at one end,as shown.A uniform magnetic field (magnitude = 0.20 T)is directed into the paper.If L = 0.40 m,what is the potential difference,V_A - V_P?

What is the inductance of a series RL circuit in which R = 1.0 K $\Omega$ if the current increases to one-third of its final value in 30 $\mu$ s?

The coil shown in the figure has 2 turns,a cross-sectional area of 0.20 m²,and a field (parallel to the axis of the coil)with a magnitude given by B = (4.0 + 3.0t²)T,where t is in s.What is the potential difference,V_A-V_C,at t = 3.0 s?

A square coil (length of side = 24 cm)of wire consisting of two turns is placed in a uniform magnetic field that makes an angle of 60 $\degree$ with the plane of the coil.If the magnitude of this field increases by 6.0 mT every 10 ms,what is the magnitude of the emf induced in the coil?

After a switch is thrown to remove the battery from a DC LR circuit,but the circuit is still left complete,the time constant represents

An inductor produces a back emf in a DC series RL circuit when a switch connecting the battery to the circuit is closed.We can explain this by

A small airplane with a wing span of 12 m flies horizontally and due north at a speed of 60 m/s in a region where the magnetic field of the earth is 60 $\mu$ T directed 60 $\degree$ below the horizontal.What is the magnitude of the induced emf between the ends of the wing?

A conducting bar moves as shown near a long wire carrying a constant 50-A current.If a = 4.0 mm,L = 50 cm,and v = 12 m/s,what is the potential difference,V_A - V_B?