Half Yearly Notes

2013 Feedback

Q11 Magnetic breaking

• Identify (basic answer) the disk slows down• Description: changing flux as new conductors enter the

area of field (generated by the electromagnet) causes eddy currents and fields that are in opposition to motion

Q11 Lenz’s Law

• From Jacaranda

• From wikipeadia• An induced electromotive force (emf) always gives rise to a current whose

magnetic field opposes the original change in magnetic flux.• So we need FLID

Q11 – lenz’s law 2

• So we need FLID, to produce an emf with changing flux – B changes, or A changes by the relative motion or rotation

• Then Lenz’s law describes the magnetic field produced

Q11 sequence

Changing Area/Field

Changing Flux (B x A) FLID emf

Conducting path eddy

current

Heating and Mag Field produced

Mag field opposes change

Causes breaking

Lenz law gives poles for eddy current magnetsThat act against the imposed magnet,Or gives the central current the by slows the diskBy the central magnet.

Q12 Laminations

Q15 Transformer

•inclusion through diagrams, equations and reference to the role of transformers in grid supply•Explain that the function of transformers allow voltage rated for home appliances, with examples•Describe transformers have a magnetically coupled core, and are step up and step down between two circuits•Identify transformers change the AC voltage between circuits

Q15Subject

Q15Subject Explain (increase use in home)

the development of transformers was necessary to enable the increased use of electrical appliances in the home.

ID Transformer, appliance in home – relevant to questionDescribe - relevant features and characteristics that help your explanationExplain – increased use of electrical appliances

Transformer

• What does it do? E-B-E• How does it do it?• What are appliances in the home?• What are their characteristics why?

Response Process

• Preparation – deconstruct – id subject – plan response – consider tables / diagrams

• Topic sentence – consider information – wider reading – use question language –link words- label diagrams

• Strategies 1 underline key words 2 decorate adjectives, adverbs, example 3 paragraphs with subheadings 4 DIY marking schemes

Q17 First hand investigation

• Identify – What the investigation is• Hypothesis to test dependant as a function of

independent• Outline steps to test hypothesis• Hypothesis confirmed when…

Space News

• Think about the near asteroid impact

Asteroid changes direction, speeds upIn Earths GPE and loses 3% speed due To sling shot (hill extimate)

Q19

Q19Subject Evaluate the validity

Weight on ear only a function of altitude, mass of object, mass of earth-

ID, Weight on earth, altitude , gravitational mass object, and earthDescribe (elaborate), validExplain. Universal law, equation

Point For AgainstAltitudeMass of earthDirection

ReducesEquationDown

Measured from centerMass uneven, atmosphereAngled

Criteria: Valid for all points,

Q19 Gravity map