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WorksheetsElectromagnetic Induction
Total questions: 85
Worksheet time: 2hrs 0mins
into a coil with twice the number of loops,
Which of the following increases frequency of AC?
increasing number of turns on the coil
using a stronger magnet
rotating the coil faster
increase area of the coil
No EMF is induced when?
When the wire is not moving
When the wire is parallel to magnetic field direction
When no lines are cut by the wire
all of the above
A permanent magnet is quickly introduced into the center of an aluminum closed ring. With this ring ...
will be attracted to the magnet;
push away from the magnet;
remain stationary;
it will start to rotate about an axis passing through its center.
Which of the devices is not based on electromagnetic induction?
Generator
electrodynamic microphone
transformer
electric motor
If the magnet falls from a certain height through the opening of the closed coil, then the acceleration of the magnet ...
is modular constant and equals free fall acceleration;
modulus of steel and greater than free fall acceleration;
modulus constant and less than free fall acceleration;
changes in modulus and less than the acceleration of free fall.
Provide the correct statements.
1. EMF self-induction occurs when passing through a DC coil;
2. Self-induction EMF occurs when passing through an AC coil;
3. EMF self-induction counteracts current flow;
4. EMF self-induction counteracts current changes.
2 & 3;
2 & 4;
1 &3
1 & 4
Determine the inductance of the coil if a 5 V self-induction EMF occurs at a rate of change of current of 10 A / s.
5 H
0,5 H
2 H
0,2 H
The induction current in the horizontally arranged coil has the direction shown in the figure. Provide statements that do not correctly explain the occurrence of this current.
1. Top of the ring is made by the N-Pole of permanent magnet.
2. Top of the ring is made by the S-Pole of permanent magnet.
3. The N-pole of the magnet is removed from the ring upwards.
4. The S-pole of the magnet is removed from the ring upwards.
Only 1;
1 & 4;
Only 2;
2 & 3.
An induction current is shown in the coil contained in the alternating magnetic field, the direction of which is shown in the figure. How does the magnetic flux that permeate the circuit change?
Does not change;
increases;
decreases;
periodically increases and decreases.
The turn is contained in a magnetic field such that the lines of induction of the magnetic field are parallel to the plane of the turn. Which statement is correct?
An induction current flows clockwise;
The induction current in the coil flows counter-clockwise;
The induction current in the coil will occur when the magnetic field induction changes;
There is no induction current in the coil.
The coil has 500 turns. When the current is changed to 2 A, the magnetic flux through each turn changes by 4 mWb. Determine the inductance of the coil.
2 H
0,2 H
1 H
0,1 H
The magnetic field energy of a coil having 500 turns is 25 J. The current in the coil is 5 A. What magnetic flux penetrates each coil coil?
10 mWb
1 mWb
20 mWb
2 mWb
The aircraft flies horizontally at a speed of 720 km / h. The wingspan of the aircraft is 20 m, the vertical component of the Earth's magnetic field is 50 µT. What is the difference in potential at the ends of the wings of the aircraft?
0.05 V
1 V
2 V
0.2 V
As the current decreases in the coil from 20 A to 10 A for 0.1 s, a self-induction of 200 V. occurs in it. What magnetic flux penetrates the coil at the instant when 15 A current flows through it?
450 Wb
30 Wb
45 Wb
22.5 Wb
The figure shows the scheme of the experiment. When the key is locked or opened, the galvanometer arrow is deflected. When will the relative position of the deflection coils be the maximum?
Which activity will produce the highest current?
Move the magnet bar into the coil while the coil remains stationery
Move the coil into the magnet bar while the magnet remains stationery
Move the coil and magnet towards each other
Move the coil and magnet away from each other
What type of current is being produced?
Alternating
Direct
Which description best applies to Lenz's Law?
An induced current occurs when a magnet passes through a tube.
When a change in magnetic field occurs to a coil the direction of current goes in the in the other direction to this change.
The direction of an induced current is such to align with the change that created it.
A magnet is a tube is always slowed by its magnetic field.
What happens to the galvanometer if the copper rod is moved upwards?
No change
Deflect to the right
Deflect to the left
Deflect to the right and left
Which action will increase the deflection of the galvanometer pointer?
The magnetic pole is reversed
The number of turns of coils is increased
The coil is made from insulated wire
The magnet is slowly pushed into the coil
The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a galvanometer. The magnet was held stationary for a few seconds with the north pole in the middle of the solenoid and then withdrawn rapidly. The maximum deflection of the galvanometer was observed when the magnet was
moving towards the solenoid
moving into the solenoid
at rest inside the solenoid
moving out of the solenoid
Two identical coaxial coils P and Q carrying equal amount of current in the same direction are brought nearer. The current in
P increases while in Q decreases
Q increases while in P decreases
both P and Q increases
both P and Q decreases
There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then
current is induced in the loop in the anti-clockwise direction.
current is induced in the loop in the clockwise direction.
ac is induced in the loop.
no current is induced in the loop.
Identify the wrong statement.
Eddy currents are produced in a steady magnetic field.
Eddy currents can be minimised by using laminated core
Induction furnace use eddy currents to produce heat
Eddy current can be used to produce braking force in moving trains.
An e.m.f is produced in a coil, which is not connected to an external voltage source. This is not due to
the coil being in a time varying magnetic field.
the coil moving in a time varying magnetic field.
the coil moving in a constant magnetic field.
the coil is stationary in external spatially varying magnetic field, which does not change with time
Which of the following does not use the application of eddy current?
Electric power meters
Induction furnace
LED lights
Magnetic brakes in trains
Direction of induced current is such that it (a) the cause which produces it.
Total number of magnetic lines of force crossing a surface normally is called (a) .
Eddy currents can be minimized using a (a) core
The north pole of a bar magnet is rapidly introduced into a solenoid at one end (say A). Which of the following statements correctly depicts the phenomenon taking place?
No induced emf is developed.
The end A of the solenoid behaves like a south pole.
The end A of the solenoid behaves like a north pole.
The end A of the solenoid acquires positive potential.
Which coil will have the largest flux?
A
B
C
D
The scenario shown induces a voltage of magnitude V. If the magnet has twice the magnetic field but its motion stopped, how would the induced voltage change?
Voltage would be twice as large in the same direction.
Voltage would be half as large in the same direction.
Voltage would be twice as large in the opposite direction.
No voltage would be induced in the coil.
As the north pole of the magnet is moved into the coil, the magnetic flux is _________.
increasing
decreasing
remains constant
depends on the speed of the magnet
Magnets and coils are moved with velocities shown. Which will NOT induce a voltage in the coil?
A circular coil of area 1.5 m2 and number of turns 200 is placed in a 1.4 T magnetic field which is perpendicular to the plane of the coil as shown in the diagram. If this magnetic field is reduced to 0.20 T in 0.01 s, what is the e.m.f. induced in the coil?
1.8 ×102 V
2.4 ×102 V
3.0 ×104 V
3.6 ×104 V
What type of current is used?
Direct
Alternating
A ring is originally oriented 30-deg from the magnetic field. Which of the following would increase the flux?
increasing the field
reversing the direction of the field
increasing 30-deg to 90-deg
decreasing 30-deg to 0-deg
A field of constant B = 0.5 T is enclosed by a ring with radius 2m. Which of the following is true?
Flux is 2π Webers and has counterclockwise current
Flux is 2π Webers and has no current
Flux is 0 Webers and has clockwise current
Flux is 0 Webers and has no current
A magnet is dropped through a copper tube. If the magnet were dropped outside the tube, it would hit the ground ________ as it did through the tube.
in more time
in less time
in the same amount of time
A magnet is dropped through a copper tube. This results in all of the following EXCEPT ________.
currents flowing in the copper tube
an induced EMF in the copper tube
an induced magnetic field inside the copper tube
a frictional force between the magnet and the tube
All of the following will result in an induced current in the loop EXCEPT
A
B
C
D
If the magnetic field were increased from B = 0.5 T to 1.0T, the flux through the loop would
increase
decrease
remain the same
If the magnetic field were increased from B = 0.5 T to 1.0T, the induced field in the loop would be directed _______
clockwise
counterclockwise
into the page
out of the page
If the magnetic field were increased from B = 0.5 mT to 1.0mT, the induced current in the loop would be directed _______
clockwise
counterclockwise
into the page
out of the page
A moveable rod makes contact along two rails with a lightbulb attached. As the rod is moved to the right, the magnetic flux _________.
increases
decreases
stays the same
A moveable rod makes contact along two rails with a lightbulb attached. As the rod is moved to the right, a magnetic field is induced _________.
counterclockwise
clockwise
into the page
out of the page
A moveable rod makes contact along two rails with a lightbulb attached. As the rod is moved to the right, a current is induced _________.
counterclockwise
clockwise
into the page
out of the page
A moveable rod makes contact along two rails of zero resistance with a lightbulb attached. As the rod is moved to the right with constant velocity, the light bulb's brightness would
get dimmer and dimmer
turn off
stay constant
increase rapidly
As the bar travels to the right, current is induced in the counterclockwise direction. What is the direction of the induced field?
clockwise
counterclockwise
into the page
out of the page
In this picture, a bar slides to the right. The flux is _______ and field is induced ________.
increasing, out of the page
increasing, into the page
decreasing, out of the page
decreasing, into the page
The magnetic field B gets weaker over time, taking 2 seconds to go to zero. During the two seconds, the current through the resistor is directed ________ and _________.
downwards (-y), decreasing in magnitude
downwards (-y), constant magnitude
upwards (+y), decreasing in magnitude
upwards (+y), constant magnitude
All of the following would increase the voltage induced by the magnet EXCEPT
increasing the speed of the motion
increasing the number of coils of wire
increasing the resistance in the coils
increasing the strength of the magnet
As the north pole of the magnet is moved out of the coil to the left, the magnetic flux is _________.
increasing
decreasing
remains constant
depends on the speed of the magnet
Which of the following would decrease the flux through this wire loop?
decreasing the area of the coil
decreasing the magnetic field of the coil
pulling the coil until it leaves the magnetic field
all of the above
The magnetic field enclosed by a 0.5 m2 wire loop increases from 0T to 3T in five seconds. Which of the following could be used to calculate the voltage in the coil?
A 0.2m by 0.3m wire is pulled at 5m/s into a magnetic field of strength 6T. Which of the following could be used to calculate the voltage in the loop?
A wire loop is pulled into a magnetic field that is directed into the page. Which direction is current induced in the coil?
Clockwise
Counterclockwise
No current
A wire loop is pulled through a magnetic field that is directed into the page but is neither entering or exiting the field. Which direction is current induced in the coil?
Clockwise
Counterclockwise
No current
A wire loop is pulled out of a magnetic field that is directed into the page. Which direction is current induced in the coil?
Clockwise
Counterclockwise
No current
The magnetic field increases from 0T to 5T in the direction shown. What direction is current induced in the wire?
Clockwise
Counterclockwise
No current
The device pictured shows
electrical energy --> kinetic energy
kinetic energy --> electrical energy
electrical energy --> electrical energy
kinetic energy --> kinetic energy
The device pictured best matches the energy transformations of a __________.
transformer
motor
generator
electromagnet
The device pictured is a ______ and its purpose is to ________.
transformer, covert high voltage to low voltage
motor, convert electricity to kinetic energy
generator, convert kinetic energy to electricity
electromagnet, convert current into magnetic field
The device pictured is a ______ and its purpose is to ________.
transformer, covert high voltage to low voltage
motor, convert electricity to kinetic energy
generator, convert kinetic energy to electricity
electromagnet, convert current into magnetic field
