Motion and Electromagnetism

What is the role of the magnetic flux density in the motor effect equation?

• It calculates the speed of the wire.

• It measures the resistance of the wire.

• It indicates the temperature of the wire.

• It determines the strength of the magnetic field.

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According to Fleming's left-hand rule, what does the thumb represent?

• Velocity of the particle

• Current through the wire

• Direction of the magnetic field

• Direction of the force

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What is the principle behind a cyclotron?

• It uses magnetic fields to decrease particle energy.

• It slows down particles for better observation.

• It uses electric fields to separate particles by mass.

• It accelerates particles using a magnetic field and alternating electric fields.

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How does a mass spectrometer use magnetic fields to separate particles?

• By changing the electric field strength

• By altering the magnetic field direction

• By using different gravitational forces

• By utilizing the magnetic field to affect particles differently based on their mass

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What does Faraday's law state about electromagnetic induction?

• The induced EMF is proportional to the rate of change of magnetic flux linkage.

• The induced EMF decreases with increased coil resistance.

• The induced EMF is independent of the magnetic field strength.

• The induced EMF is constant regardless of flux changes.

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What is the purpose of Lenz's law in electromagnetic induction?

• To calculate the exact value of the induced EMF

• To predict the direction of induced current that opposes the change causing it

• To increase the efficiency of energy conversion

• To reduce the magnetic field strength automatically

How does a transformer adjust the voltage in electrical power transmission?

• By switching the current type from AC to DC

• By changing the number of turns in the coils

• By altering the resistance in the circuit

• By modifying the core material

What is the effect of the motor load on the back EMF in an electric motor?

• Motor load has no effect on the back EMF

• Higher load decreases the back EMF

• Motor load only affects the motor's temperature, not the EMF

• Higher load increases the back EMF

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What is the primary reason for using AC in the primary coil of a transformer?

• To reduce the overall power consumption

• To increase the magnetic field strength

• To induce a voltage in the secondary coil

• To simplify the design of the transformer

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Why are overhead cables in the National Grid not made of copper?

• Copper is too expensive and heavy

• Copper is not durable enough for outdoor use

• Copper does not conduct electricity well

• Copper cables are too flexible for overhead use