Week 1

Question 1

What is force, how do you calculate it and what is it measured in?

Answer 1

• the ability to move an object from stationary/change direction
• f = ma
• measured in N (1N = 1kg m^-2)

Question 2

What is work (also what is electrical work), how is it calculated and what is it measured in?

Answer 2

• force required to move a body over a distance
• force x distance / charge x voltage
• measured in joules
• electrical work (measured in eV) is the work done to move an electron through a potential difference of 1V

Question 3

what is energy and what are the types, how is energy converted in x-ray?

Answer 3

• measure of the ability to do work
• potential, kinetic, thermal, electromagnetic
• in x-ray, electrical potential energy (because of voltage/potential difference) –> electron kinetic energy (as it travels from cathode to anode) –> electromagnetic energy (x-rays) and thermal energy (heat) (from interactions with nucleus and other electrons)

Question 4

what is power, how is it calculated and what is it measured in?

Answer 4

• rate at which energy is used (converted)
• power = current x voltage
• joules/second (watt)

Question 5

what is heat and its mechanisms of transfer?

Answer 5

• flow of thermal energy from high to low temp
• conduction (solid contact), convection (carried by liquid/gas), radiation (electromagnetic waves)

Question 6

what are waves and its two types?

Answer 6

• travelling disturbance, carries energy from place to place
• longitudinal (straight line e.g. sound)
• transverse (oscillates e.g.electromagnetic wave)

Question 7

what is magnetism and ferromagnetic materials?

Answer 7

• property of materials arising from intrinsic spin and orbital motion of electrons
• ferromagnetic materials have groups of atoms with naturally aligned orbital spins, forming magnetic regions

Question 8

what is an electric current and what is its power determined by, what is the difference between electrical conductors/insulators?

Answer 8

• flow of electrons around a circuit, caused by potential difference (voltage)
• power is determined by current and voltage
• conductors have loosely bound electrons, insulators have tightly bound electrons

Question 9

what are the properties of electromagnetic rays (x-rays)?

Answer 9

• short wavelength, high frequency, high energy
• travels at the speed of light