National 5 Physics Flashcards

Flashcards for National 5 Physics - Radiation, Waves, Electromagnetism, and Dynamics

Atom

Consists of protons (positively charged) and neutrons (no charge) in the nucleus, surrounded by orbiting electrons (negatively charged).

Ionisation

The process whereby an atom gains or loses an electron.

Alpha Particle

A helium nucleus consisting of 2 protons and 2 neutrons (zero electrons).

Beta Particle

A fast moving electron that is ejected from the nucleus of an atom undergoing nuclear decay.

Equivalent Dose Rate

The equivalent dose per unit time.

Half-Life

The time it takes for the activity of a radioactive source to decrease to half of its original value.

Nuclear Fission

When a nucleus of a large mass number splits into two daughter nuclei of smaller mass number, releasing neutrons and energy (heat).

Nuclear Fusion

When two nuclei of smaller mass number join together to create a larger nucleus of greater mass number.

Gamma Ray

An electromagnetic wave of high frequency.

Chain Reaction

Neutrons released by a nuclear reaction go on to produce further fission reactions.

Activity

The number of nuclei decaying per second (i.e., the rate of nuclei decaying).

Background Radiation

Ionising radiation which is present all the time and can be natural or artificial.

Absorbed Dose

The energy absorbed per unit mass of the absorbing material.

Radiation Weighting Factor

Assigned to each type of ionising radiation to account for differing levels of ionisation densities and biological effects.

Fuel Rods

Made of uranium-238 enriched with uranium-235, producing energy by nuclear fission.

Moderator

Slows down neutrons produced in fission, since slow neutrons split a nucleus more easily.

Control Rods

Absorb neutrons; when lowered into the core, they stop the chain reaction.

Coolant

Cools the reactor and transfers heat to boilers (e.g., carbon dioxide in gas-cooled reactors).

Containment Vessel

Made of thick concrete, acts as a shield to absorb neutrons and other radiations.

Equivalent Dose

The product of absorbed dose and radiation weighting factor.

Wave

Periodic disturbance that transfers energy from one place to another.

Transverse Wave

A wave whose oscillations are perpendicular to the direction of energy transfer; can travel through a medium and a vacuum.

Longitudinal Wave

A wave that causes particles to oscillate parallel to the direction of energy transfer; requires a medium to travel through.

Equilibrium Position

The rest position of the wave.

Crest

The highest point of a wave.

Trough

The lowest point of a wave.

Amplitude

Vertical distance from the equilibrium position to either the crest or trough.

Frequency

Number of waves that pass a particular point per second.

Period

Time taken for one complete wave to pass a point.

Wavelength

The horizontal distance between identical points on consecutive waves.

Wave Speed

The distance the wave travels each second.

Diffraction

The effect of waves bending around an obstacle or spreading out after passing through a gap.

Electromagnetic Spectrum

A family of waves which all travel at the speed of light in a vacuum (3.0 x 10^8 m/s); transverse and able to travel through a vacuum.

Normal

A dotted line that exists at 90 degrees to the boundary between two mediums of differing optical density.

Reflection

When a particular frequency of electromagnetic wave returns from a surface.

Refraction

The process whereby a wave experiences a change in speed (and wavelength) when it crosses a boundary between two mediums of differing optical density.

Dispersion

The process whereby white light is separated into its component colours due to refraction.

Total Internal Reflection

When a ray of light reaches the boundary to a less optically dense medium at an angle of incidence which exceeds the critical angle, the ray is completely reflected within the first (more optically dense medium).

Lens

An object made of transparent material which is designed to refract waves.

Converging Lens

A lens with a convex shape designed to cause rays to converge towards one another.

Diverging Lens

A lens with a concave shape designed to cause rays to diverge away from one another.

Short Sight

Able to see close objects clearly but distant objects appear blurred; corrected using a concave lens.

Long Sight

Able to see distant objects clearly but close objects appear blurred; corrected using a convex lens.

Scalar

A physical quantity that possesses magnitude and a unit only.

Vector

A physical quantity that possesses a direction, magnitude and a unit.

Distance

The path length from the start point to the finish point.

Displacement

The straight line distance from the start point to the finish point.

Speed

The rate of change in distance.

Velocity

The rate of change in displacement.

Resultant

The equivalent to the produced effect of two or more component vectors acting at the same point.

Acceleration

The rate of change in velocity.

Force

The interaction between objects that causes them to change their motion and/or shape.

Newton's First Law of Motion

An object will continue to travel at a constant speed in a straight line, or stay at rest, unless acted on by an unbalanced force.

Newton's Second Law of Motion

The acceleration of an object is directly proportional to the magnitude of the unbalanced force acting upon it and inversely proportional to its mass.