Electromagnetism Chapter 4: Induction, Generators, and X-Ray Transformers

What is the atomic nature of magnetism?

Magnetism is produced by the motion of electric charges, resulting in attractive and repulsive forces.

What are Fleming's hand rules used for?

They are used to determine the direction of current flow and magnetic field in electromagnets.

How does a solenoid function?

A solenoid is a coil of wire that generates a magnetic field when an electric current passes through it.

What is electromagnetic induction?

The process of generating an electric current by changing the magnetic field around a conductor.

What types of movement can produce electromagnetism?

Movement of a conductor across a magnetic field, movement of the magnetic field, or varying the magnetic flux.

What factors regulate the strength of electromagnetic induction?

The strength of the magnetic field, the speed of movement, and the angle of movement between the conductor and magnetic field.

What is self-induction?

A phenomenon where a changing electric current induces an electromotive force (EMF) across the coil itself.

What is the function of a transformer?

To change the voltage and current levels in an alternating current (AC) circuit.

What is the transformer law?

It states that the ratio of the primary to secondary voltage is equal to the ratio of the number of turns in the primary to secondary coils.

What is an autotransformer?

A type of transformer that has a single winding that acts as both the primary and secondary winding.

What is the orbital magnetic moment?

The magnetic force created by a charged particle in motion, perpendicular to its direction of motion.

What are lines of force in magnetism?

They represent the magnetic field around a magnet and indicate the direction of magnetic force.

What is the relationship between magnetic field strength and lines of flux?

A stronger magnetic field has a greater number of lines of flux, indicating higher flux density.

What are the classifications of magnets?

Natural magnets, artificial permanent magnets, and electromagnets.

What happens to a non-magnetized iron bar in a magnetic field?

Its dipoles align with the lines of force, but return to their original state when removed from the field.

What are the two general characteristics of materials regarding magnetism?

Permeability (ability to become magnetized) and retentivity (ability to hold magnetic properties).

What is mutual induction?

when current flows through the first coil induces an EMF in the second coil

What is a generator?

A device that converts mechanical energy into electrical energy, producing either direct current (DC) or alternating current (AC).

What is the frequency of an AC generator operating in the US?

60 Hz, meaning the direction of electron flow changes 60 times per second.

What type of wave is produced by an AC generator?

A sine wave.

What components are found in an AC generator?

Armature, magnets, slip rings, and brushes.

What is the unit of frequency?

Hertz (Hz), where 1 cycle per second equals 1 Hz.

What is the frequency of electricity in the rad department?

60 Hz, resulting in 120 changes (pulses) per second.

What characterizes Direct Current (DC)?

It is uni-directional, meaning the flow of charge is always in the same direction.

What is the function of a commutator ring in DC generators?

It replaces slip rings in AC generators and ensures the current flows in one direction.

What is a key feature of multiple-coil DC generators?

They utilize numerous coils and a commutator divided into a corresponding number of segments.

What is the purpose of a motor?

To produce mechanical motion when supplied with electrical current.

What are the main components of a motor?

Rotor and Stator.

What is a synchronous motor?

A motor where coils turn at the same rate as the armature supplying current.

What is an induction motor?

An asynchronous motor that operates at variable speeds, often used in rotating anode x-ray tubes.

What is the function of a galvanometer?

To indicate current for DC when permanent magnets are used.

What does an ammeter measure?

Current flow (amps) and is connected in series.

What does a voltmeter measure?

Potential difference between two points in a circuit (volts) and is connected in parallel.

What is the principle of operation for transformers?

They work on the principle of mutual induction and Ohm's law to change (regulate) voltage.

What is the turns ratio in a transformer?

The ratio of the number of turns in the secondary coil to the number of turns in the primary coil (TR = Ns/Np).

What does a step-up transformer do?

Increases voltage from primary to secondary side, having more secondary coils than primary.

What does a step-down transformer do?

Decreases voltage from primary to secondary side, having fewer secondary coils than primary.

How can the strength of the magnetic field in a transformer be increased?

By increasing the current, the number of turns in the coil, or using a ferromagnetic core.

What happens if a step-up transformer fails?

Not enough voltage will reach the tube for x-ray production.

What is the relationship between voltage and turns ratio in transformers?

If TR > 1, it is a step-up transformer; if TR < 1, it is a step-down transformer.

If a transformer has 100 turns in the primary and 20,000 turns in the secondary with 400 volts supplied, what is the voltage in the secondary coil?

The voltage in the secondary coil will be 80,000 volts.

What is the equation that combines the Transformer Law with Ohm's Law?

Is/Ip = Vp/Vs and Is/Ip = Np/Ns

What does 'I' represent in the Transformer Law?

Current in amperes

How are voltage and number of turns related in a transformer?

Voltage and number of turns are directly proportional.

How does a step-up transformer affect voltage and amperage?

It increases voltage from primary to secondary while decreasing amperage.

What is the efficiency of transformers?

Transformers have a 95% efficiency.

What is the purpose of a high voltage transformer in x-ray equipment?

To step up the voltage into the kV range.

What are the types of transformers mentioned?

Air Core, Open Core, Closed Core, Shell type.

What does the autotransformer provide in the x-ray circuit?

Induced voltage to the primary side of the high voltage transformer.

What is the role of the high-voltage step-up transformer in the x-ray circuit?

To raise the incoming-line voltage to the kV range needed for x-ray production.

What is the function of the filament step-down transformer?

To decrease the incoming-line voltage to the 5 to 15 volt and 3 to 5 ampere range used to heat the tube filament.

What is the principle of self-induction in an autotransformer?

It operates on the principle of self-induction with a single winding of wire incorporating both primary and secondary coils.

How is voltage adjusted in the autotransformer?

By selecting secondary turns (taps) using the kVp select control.

What is the principle of mutual induction in a step-up transformer?

Electricity flowing through the primary coil induces electricity to flow in a second wire placed within the magnetic field.

What determines the voltage boost in a step-up transformer?

The turns ratio, which compares the number of turns in the primary coil to the secondary coil.

What happens to the voltage in the secondary coil of a step-up transformer?

It is boosted to the kV level.

What is the relationship between turns ratio and resulting kV in a transformer?

The greater the turns ratio, the higher the resulting kV.