Definitions

Question 1

Absolute Zero

Answer 1

The lowest possible temperature at which substances have the minimum internal energy

Question 2

Acoustic Impedence

Answer 2

The product of the density of a substance and the speed of ultrasound in that substance

Question 3

Attenuation

Answer 3

The decrease in the intensity of electromagnetic radiation as it passes through matter or space

Question 4

Brownian motion

Answer 4

The continuous random motion of small particles suspended in a fluid, visible under a microscope

Question 5

Delete

Answer 5

Two waves sources, or waves, that are coherent have a constant phase difference

Question 6

Coupling gel

Answer 6

A gel with the acoustic impedance similar to that of skin, that is smeared onto the transducer and the patients skin before and ultrasound scan in order to fill air gaps and ensure that almost all the ultrasound enters the patients body

Question 7

Decay constant

Answer 7

The probability of a decay of an individual nucleus per unit of time

Question 8

Ideal gas

Answer 8

A model of a gas including assumptions similar to the behaviour of a real gas

Question 9

Inelastic collision

Answer 9

A collision in which kinetic energy is transferred into other forms and is NOT conserved

Question 10

Interference pattern

Answer 10

A pattern of constructive and destructive interference formed as waves overlap

Question 11

Kirchoff’s First law

Answer 11

At any point in an electrical circuit, the sum of currents into that point is equal to the sum of the currents out of that point. Electrical charge is conserved

Question 12

Kirchoff’s Second law

Answer 12

In a closed loop of an electrical circuit, the sum of the EMF’s is equal to the sum of the PD’s

Question 13

Internal resistance

Answer 13

The resistance of a source of EMF due to its construction which causes a loss in energy/voltage as the charge passes through the source

Question 14

Magnetic field lines

Answer 14

Lines of force drawn to represent a magnetic field pattern

Question 15

Magnetic flux

Answer 15

The product of the component of the magnetic flux density perpendicular to a given area and that cross-sectional area. ø = BACosθ

Question 16

Newtons first law of motion

Answer 16

A body will remain at rest of continue moving at a constant velocity unless acted upon by a resultant force

Question 17

Newtons Second Law of Motion

Answer 17

The net force acting on an object is equal to the product of its mass and acceleration in the direction of the force.

Question 18

Newtons Third Law

Answer 18

When two objects interact, each exerts and equal but opposite force and takes place in direction of the force

Question 19

Newtons Laws of gravitation

Answer 19

The force between two point masses is directly proportional to the product of the masses and inversely proportional to the square of the separation between them

Question 20

Binding energy

Answer 20

The minimum energy required to completely separate a nucleus into its constituent protons and neutrons

Question 21

Gravitational Field

Answer 21

A field created around any object with mass, extending to infinity, but diminishing as distance from the centre of mass of the object increase

Question 22

Gravitational field strength

Answer 22

The gravitational force exerted per unit of mass at a point within a gravitational field

Question 23

Gravitational potential

Answer 23

The work done per unit of mass to bring an object from infinity to a point in the gravitational field

Question 24

Gravitational potential energy

Answer 24

The capacity for doing work as a result of an objects position in a gravitational field