Exam 31: Faradays Law

A coil is wrapped with 300 turns of wire on the perimeter of a square frame (side length = 20 cm).Each turn has the same area as the frame,and the total resistance of the coil is 1.5 Ω.A uniform magnetic field perpendicular to the plane of the coil changes in magnitude at a constant rate from 0.50 T to 0.90 T in 2.0 s.What is the magnitude of the induced emf in the coil while the field is changing?

A conducting bar of length L rotates in a counterclockwise direction 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_B?

A 400-turn circular coil (radius = 1.0 cm)is oriented with its plane perpendicular to a uniform magnetic field which has a magnitude that varies sinusoidally with a frequency of 90 Hz.If the maximum value of the induced emf in the coil is observed to be 4.2 V,what is the maximum value of the magnitude of the varying magnetic field?

A long straight wire is parallel to one edge and is in the plane of a single-turn rectangular loop as shown.If the loop is changing width so that the distance x changes at a constant rate of 4.0 cm/s,what is the magnitude of the emf induced in the loop at an instant when x = 6.0 cm? Let a = 2.0 cm,b = 1.2 m,and I = 30 A.

In a demonstration,a 4.00 cm² square coil with 10000 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 4000 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

Starting outside the region with the magnetic field,a single square coil of wire moves across the region with a uniform magnetic field Perpendicular to the page.The loop moves at constant velocity )As seen from above,a counterclockwise emf is regarded as positive.Roger claims that the graph shown below represents the induced emf.Martin says he's wrong.In which direction did the loop move over the plane of the page,or is Martin correct?

A current may be induced in a coil by

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?

A conducting rectangular loop of mass M,resistance R,and dimensions a × b is allowed to fall from rest through a uniform magnetic field which is perpendicular to the plane of the loop.The loop accelerates until it reaches a terminal speed (before the upper end enters the magnetic field).If a = 2.0 m,B = 6.0 T,R = 40 Ω,and M = 0.60 kg,what is the terminal speed?

A 5-turn square loop (10 cm along a side,resistance = 4.0 Ω)is placed in a magnetic field that makes an angle of 30° with the plane of the loop.The magnitude of this field varies with time according to B = 0.50t²,where t is measured in s and B in T.What is the induced current in the coil at t = 4.0 s?

A long solenoid (radius = 3.0 cm,2 500 turns per meter)carries a current given by I = 0.30 sin(200 t)A,where t is measured in s.When t = 2.5 ms,what is the magnitude of the induced electric field at a point which is 4.0 cm from the axis of the solenoid?

A rod (length = 10 cm)moves on two horizontal frictionless conducting rails,as shown.The magnetic field in the region is directed perpendicularly to the plane of the rails and is uniform and constant.If a constant force of 0.60 N moves the bar at a constant velocity of 2.0 m/s,what is the current through the 12-Ω load resistor?

A 40-turn circular coil (radius = 4.0 cm,total resistance = 0.20 Ω)is placed in a uniform magnetic field directed perpendicular to the plane of the coil.The magnitude of the magnetic field varies with time as given by B = 50 sin(10 πt)mT where t is measured in s.What is the magnitude of the induced current in the coil at 0.10 s?

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?

The magnetic flux through a loop perpendicular to a uniform magnetic field will change

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 long solenoid (n = 1 500 turns/m)has a cross-sectional area of 0.40 m² and a current given by I = (4.0 + 3.0t²)A,where t is in seconds.A flat circular coil (N = 300 turns)with a cross-sectional area of 0.15 m² is inside and coaxial with the solenoid.What is the magnitude of the emf induced in the coil at t = 2.0 s?

A circular loop (area = 0.20 m²)turns in a uniform magnetic field with B = 0.13 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is (π)rads and is decreasing at the rate of 0.50 rad/s,what is the magnitude of the emf induced in the loop?

A car with a radio antenna 1.0 m long travels at 80 km/h in a locality where the Earth's magnetic field is 5.0 × 10−⁵ T.What is the maximum possible emf induced in the antenna as a result of moving through the Earth's magnetic field?

A coil is wrapped with 300 turns of wire on the perimeter of a circular frame (radius = 8.0 cm).Each turn has the same area,equal to that of the frame.A uniform magnetic field is turned on perpendicular to the plane of the coil.This field changes at a constant rate from 20 to 80 mT in a time of 20 ms.What is the magnitude of the induced emf in the coil at the instant the magnetic field has a magnitude of 50 mT?