CORRECTLY ANSWERED QUESTIONS LATEST
UPDATE
1). What direction do magnetic field lines move in?
Ans: North moves to south on the "outside" of the magnet, south moves through north
"inside" the magnet
2). What does the closeness of the lines mean in a magnetic field?
Ans: The closer the lines, the stronger the magnetic field
3). Describe the force between a magnetic object and a magnet
Ans: A magnetic object is always attracted to a magnet, no matter the poles
4). Where is a magnet strongest?
Ans: At its poles
5). How can compasses be used to draw magnetic fields?
Ans: By placing paper over a magnet and holding a compass over it, the compass will
show the direction of the field lines and allow you to trace them
6). What's the difference between permanent and induced magnets?
Ans: Permanent generate their own magnetic field whereas induced are turned into
magnets in the presence of a magnetic field
7). What is produced when a current flows through a wire?
Ans: A magnetic field, in the form of concentric circles perpendicular to the wire
8). What method can be used to dictate the direction of the magnetic field?
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, Ans: The right hand rule
9). What is the right hand rule?
Ans: Using your right hand, point your thumb in the direction of current and curl your
fingers. The direction of your fingers is the direction of the field
10). What is a solenoid?
Ans: A coil of wire carrying a current
11). Describe the magnetic field inside a solenoid
Ans: It is strong and uniform
12). How can a solenoid be strengthened even more?
Ans: Place an iron core inside the coil, causing it to act as an induced magnet. This
makes it an electromagnet, as the current can be turned on and off.
13). How can an electromagnet be made stronger?
Ans: Increase current/voltage, increase no. of coils, use an iron core
14). How can the current in an electromagnet be reversed?
Ans: Swapping the direction of the batteries/power source
15). What are some uses of electromagnets?
Ans: Electric bells, use in scrapyards
16). How does an electric bell work?
Ans: An electromagnet is connected with a switch, power supply, metal arm an a
gong. When the circuit is completed, the metal arm is attracted to the electromagnet and
hits the gong. This breaks the circuit, turning off the electromagnet and resetting the
system.
What is the motor effect?
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, 17).
Ans: When a wire is placed between magnetic poles, the interaction between the two
fields induces a force on both wire and magnet, causing the wire to move
18). How does angle of the wire affect the potency motor effect?
Ans: The wire experiences the full force at 90 degrees to the magnetic field. If the wire
is parallel to the magnetic field, it will feel no force. Some force is felt between these.
19). At what angle does the force act during the motor effect?
Ans: It acts at the right angle to the magnetic field of the magnets, and in the direction
of the current of the wire
20). How does the force change when the strength of the magnetic field increases?
Ans: The magnitude of the force increases
21). What is the equation for force in relation to the motor effect when the current is
perpendicular to the magnetic field?
Ans: Force = Magnetic Flux Density * Current * Length (F=BIl)
22). What is fleming's left hand rule?
Ans: Point your index finger in the direction of the field, the middle finger in the
direction of the current and your thumb should then point in direction of motion
23). What does fleming's left hand rule show?
Ans: That if either current or magnetic field is reversed, the direction of the force will
also be reversed
24). How is a dc motor set up?
Ans: A coil with two arms is placed between magnetic poles and connected with a
split-ring commutator and suspended by spindles
25). How does a dc motor work?
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, Ans: Because the coil is on a spindle, one arm moves up whereas the other moves
down to create a rotation. The split-ring commutator swaps the contacts every half turn
to keep the motor moving in the same direction
26). How can the rotation of a dc motor be reversed?
Ans: Reverse the poles or reverse the DC current direction
27). How are loudspeakers setup?
Ans: A coil of wire is wrapped around one pole of a permanent magnet which is
surrounded by the other pole of the magnet. This coil is attached to a paper cone
28). How do loudspeakers work?
Ans: When AC current travels through the coil, the motor effect forces it to move. It
reverses when the current reverses. This variation in current causes the cone to vibrate,
causing variations in sound pressure and creating a sound wave with the same
frequency as the current
29). What is the generator effect?
Ans: The induction of potential difference (and current in a complete circuit) in a wire
moving relative to a magnetic field or experiencing a change in magnetic field
30). How can the generator effect be induced?
Ans: By moving a magnet through a coil, "cutting" the magnetic field lines and
inducing potential difference and current in a complete circuit. By moving the magnet in
the inverse direction, you can reverse the current. By moving it backwards and forwards,
you can create an AC
31). How does induced current in a generator try to resist the change?
Ans: The second magnetic field created during the generator effect acts against the
charge made in it
32). How can the size of induced pd be increased in the generator effect?
Ans: Increase the speed of movement and magnetic field strength
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