Rad science II - Test 2 - worksheets: 5-4 Magnetism, 5-5 Electromagnetic Effect Electromagnetic Induction, 5-6 Electric Generators and Motors, 5-7 The Transformer
A 110 V heater requires 15 A. What is the power consumption?
1650 W
A fluoroscope is operated at 95 kVp, 2 m. What is its power consumption?
190 W
What power is required for a radiographic exposure at 76 kVp, 500 mA?
38 W
How much current will a 60 W light bulb draw from a 120 V receptacle?
500 mA
Electric current waveforms are graphs of:
Electric current vs. time Electric voltage versus time
The electric generator is most closely associated with experiments conducted by:
Faraday
Which scientist is associated with the early development of electromagnetism?
Faraday
Which of the following is most related to electromechanical devices? - Edison's law of electromechanics - Faraday's experiment - Len'z first law of electromagnetic - Oersted's experiment on mutual induction - The voltaic pile
Faraday's experiment
Electromechanical devices?
Generators and motors
A difference between self-induction and mutual induction is that:
Mutual induction requires two coils and self induction requires only one
The turns ratio is defined as:
Number of secondary windings divided by primary windings
The experimental link connecting electric and magnetic forces was discovered by?
Oersted
Classifications of magnetism?
Paramagnetism Diamagnetic non-magnetic
A navigational compass:
has both a north and south pole
When an electric current is induced by mutual induction, such current flows:
in the secondary coil
When a transformer is designed, the change in current is:
inversely proportional to the turns ratio
Given a closed loop of wire with no electron flow, an electric current can be induced if:
A changing magnetic field is present
In an electric generator:
A oil of wire is rotated in a magnetic field
A transformer with a turn ratio of 1000:1 is
A step-up transformer
The principal difference between a solenoid and an electromagnet is magnetic field ___.
Intensity
The transformer law?
Is/Ip = Np/Ns
A modern dry-cell battery is a source of?
Joule per coulomb
An induction motor is used in an x-ray imaging system to:
rotate the anode
In an induction motor, the only part to be rotated is the:
rotor
Transformer designed used in x-ray imaging system?
shell type
Most magnetic materials are:
still magnets when broken
The physical laws of magnetism requires:
that there be a south pole for every north pole
The transformer changes:
the amplitude of the voltage
When a step-up transformer is in use:
the secondary voltage is greater than the primary voltage
If two bar magnets suspended in space were brought together, what would happen?
they would rotate and attract
T/F Laminated transformer cores are more efficient than unlaminated ones.
true
T/F: Generators and motors both require commutators.
true
A transformer "transforms" or changes electric ___.
voltage
What is EMF (Electromotive force) expressed in?
volts
Hydrogen nucleus has an associated magnetic field?
yes
The voltaic pile consist of?
zinc and copper plates sandwiched together
If two magnets are brought together, north-to-north poles will ___, whereas north-to-south poles will ____.
north to north would repel north to south would attract
If DC is applied to the primary coil of a step-up transformer, what is the result in the secondary coil?
nothing
The electric current produced by an AC generator has:
Alternating positive and negative intensity
The device designed to measure electron flow in a conductor is known as an?
Ammeter
Theoretically, conduction electrons come to rest momentarily:
At zero crossing
What us the transformer that looks like a square donut called?
Closed-core
An autotransformer:
Contains a single coil that services as both primary and secondary coils
The fact that an electric current is induced if the conductor is in a changing mantic field is known as what law?
Faraday's law
One law of electromagnetic states that:
The induced current flows in the opposite direction of the inducing action
If a transformer produces a large secondary current from a small primary current:
The turns ratio will be less than 1
The main difference between an AC and DC Electric generator isL
The type of commutator rings
If a bar magnet were suspended in space and another bar of nonmagnetic material were brought close to it, what would happen?
nothing
A transformer operates:
on AC but not on DC
The magnetic field produced by an electromagnet has:
properties similar to a bar magnet
Which of the following is based on electromagnetic induction? - AC current - Battery - DC current - Radio reception - Solenoid
radio reception
What is an electromagnet?
a coil of wire wound around an iron core
Electric ranges, air conditioners, and furnaces require 220 V, 60 Hz AC. Therefore, compared with most household appliances, they require?
a higher electric potential
An electron moving in a conductor produces?
a magnetic field perpendicular to the conductor
A lodestone is an example of?
a natural magnet
An example of ferromagnetic material?
a natural magnet
An example of a magnetic domain is?
a nucleus
The term electromagnetic induction refers to the production of?
an electric current
Primary to secondary coupling in a transformer is enhanced by:
an iron core
When an AC source is connected to a coil of wire:
an opposite EMF is induced
Most magnets:
are attracted by another magnetic field
The earth's magnetic field is strongest:
at the poles
When iron is brought near a permanent magnet, the lines of the magnetic field are:
attracted to the iron
The principal application of a transformer in an x-ray imaging system is to:
change voltage
When the right-hand rule is applied to a straight wire, the thumb indicates the direction of the?
electric current
In an electric motor:
electric current is suppled to a coil of wire
The output current in a step-up transformer is:
lower than the input current
Transformers have iron cores to intensify the:
magnetic field
A physical property that we cannot sense?
magnetism
The magnetic field produced in a transformer is based on?
mutual induction