General Physics 2 Term Test

FARADAY’S LAW

A change in magnetic field, area, or angle will induce an EMF in a loop of wire

FARADAY’S LAW

Let us calculate how much EMF - and therefore, how much current - will be induced in a loop of wire by a change in magnetic flux.

MAGNETIC FLUX DENSITY

Essentially a measure of the magnetic field running through a loop of wire

MAGNETIC FLUX DENSITY

a measurement of the total magnetic field which passes through a given area; continuous and closed

weber per square meter

unit for flux

LENZ’S LAW

an induced current will be in such a direction as to produce a magnetic field that will __oppose__ the motion of the magnetic field that is producing it. 

LENZ’S LAW

Says that the __magnetic field__ generated by the induced current will be in the __direction__ **opposite** the change __magnetic flux__

Neutron

Mass - proton

Proton

Atomic number

Mass

proton + neutron (nucleus)

stable

if there are equal amounts of protons and neutrons

spontaneous

This radioactive decay is completely

radiation

The energy that is released from the nucleus of the atom is

ALPHA PARTICLE

made of 2 protons and 2 neutrons; this means they have a charge of +2 and a mass of 4

Emits a helium nucleus; excess neutrons cause repulsion

ALPHA PARTICLE

relatively slow and heavy (takes time)

ALPHA PARTICLE

low penetrating power - you can stop them with just a sheet of paper

ALPHA PARTICLE

Because they have a large charge, alpha particles ionize (pull electrons from) other atoms strongly; noble gasses

BETA PARTICLE

have a charge of - 1 and a mass of 1/2000th of a proton (they have the same mass of an electron)

Emits an electron; excess neutrons cause conversion

BETA PARTICLE

fast and light (adding electron)

medium penetrating power - they are stopped by a sheet of aluminum or plastics

ionize atoms that they pass, but not as strongly as alpha particles do.

GAMMA RAY

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are waves, not particles; no mass and no charge

Emits a photon; nucleus energy too high

GAMMA RAY

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* we don’t find pure __ sources - they are emitted __alongside__ alpha or beta particles.
* __ emission isn’t radioactive decay because it __doesn’t__ change the state of the nucleus. it just __carries__ away some energy.

GAMMA RAY

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* high penetrating power - it takes a thick sheet of metal such as lead, or concrete to reduce them significantly
* do not directly ionize other atoms, although they may cause atoms to emit other particles which will then cause ionization

ISOTOPE NOTATION

includes additional information about an isotope.

NUCLEAR DECAY REACTIONS

Some elements are naturally unstable

They tend to undergo alpha-decay or beta-decay to become more stable.

series decay

They may take several steps in order to achieve this, thus we observe decay chains (also known as __ ) for most radioactive elements

Y-axis

Mass number in intervals of four

X-axis

number of protons in intervals of one

HALF LIFE

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* When radioactive isotopes decay, they do so exponentially.
* Their rate of decay is determined through an understanding of ___ .

HALF LIFE

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* is the amount of time it takes for __half__ of the atoms of an unstable isotope to __decay__.
* Atoms with __short__ ___ are __more unstable__ than those with long __.

Gravity

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* holds all objects with mass together (from stars to dust)

Electromagnetic Force

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* Holds the electrons in orbit around the (positively charged) nucleus of an atom
* Binds atoms together in molecules and solids

Strong Force

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* Holds all the positively charged protons and neutral neutrons together in the __nucleus__

Weak Force

Holds all the quarks together in a proton and neutron (gaps between neutron and proton), nuclear processes

NUCLEAR POWER

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* A method of generating electricity
* A means of powering large vessels, such as submarines and aircraft carriers
* Based on a process involving atomic nuclei: *nuclear fission*

FISSION

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* __splits__ the atom into two new elements, releasing energy, gamma rays and additional neutrons.
* One larger element (anything above Iron) split apart to create two smaller elements.
* This is favored by nature because this process also releases energy
* the process of splitting an atom

Chain reaction

* A __neutron__ collides with a uranium atom.
* The collision releases energy, and three additional neutrons.
* Each neutron in turn collides with additional uranium atoms.

If enough Uranium is present, the reaction becomes self-sustaining.

critical mass

The minimum amount of material needed to sustain an uncontrolled chain reaction, and therefore cause a nuclear explosion.

purity of U-235

Nuclear fuel in a reactor is about 5% U-235. For a weapon, U-235 needs to be about 90% pure.

an explosion cannot occur

The purity of U-235 in nuclear fuel is too low to sustain an uncontrolled chain reaction

meltdown

Overheating of reactor core due to loss of cooling ability or control rod function.

regular operations

As uranium fuel is used, it and its byproducts are highly radioactive.

cell damage

Radioactivity damages cell components and causes mutations.

FUSION

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* For light elements (up to Iron), fusing two elements together creates a larger element and energy.
* the process by which multiple small atomic nuclei join together to form a heavier nucleus.
* This is favored by nature because this process __releases__ energy.

smaller

* The larger element has a _______ mass than the total mass of the parts that make it up. (in terms of energy released)
* Mass of heavy element < mass of two light elements

The **difference** in mass is converted into released energy.

FUSION

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* This only happens in the sun and stars

Theory of Relativity

E = mc2