Mocks Exam Mistskes

Question 1

When talking about the electrons leaving capacitor, make sure to take what direction fincurrent

Answer 1

Not conventional

Question 2

Avadgae current in the resistor?

Answer 2

Cslcuskte total charge

Divide by time between esch throw / discharge as this is average

Question 3

Why does current not double roughly when you double frewuencyn

Answer 3

Because now the period is = to the time constsnt, meaning for every switch only 37 % can be discharged , and so as the capacitor cannot fully discharge this is why

Question 4

How ti find time constsnt ridiculous PAG

Answer 4

Lit measure until 37 % and that’s it

Question 5

Damon remember if resistance decreases, instils current Gina

Answer 5

Increase by same amount, but the time constsnt gonna. Decrease

Question 6

When separation happens in a. Capacitor what happens

Answer 6

The capacistcne etc will change but the CHARGE WOMT CHAMHE

Even voltage etc will change but charge won’t, so energy dihbele

Question 7

How ti find uncertainty using gradient s

Answer 7

Find a worst fit straight line throihgh error hard

Difference between edt and worst / best x 10

Question 8

Uncertainties

Answer 8

Absolute is smallest reading , so ruler is 1 mm, vernier 0,1 etc

Adding subtract add absolute

Multiply dividing add percentage ucneritiaited

Repeated data, then half range (1/2 biggest - smallest)

And if it’s upper and lower bounds, find the value of upper and lower, and subtract and half it

Question 9

Okay why good equipment

Answer 9

Because csn measure max
- time constsnt means percentage uncertainty less
- time constsnt means thst like 50s willmelapse before can’t make resdings anymore, which is ample enough readings ti make a graphs

Question 10

Why voltsge the same
£ grown

Answer 10

Series, so charge swme, capacitance swme, gonna end up at swme viktsge

Question 11

HOW TO DO ABSOLUTR FOR HRAOHS

Answer 11

Draw best fit calm

Now draw the worse fit from bottom of Ken to top of other

Find the difference in gradient , this is uncertainty

Unsure swme decimal

Question 12

If horizontal force applied to circular motion what happens

Answer 12

Helical loop

Question 13

Remember foil in MAGENTIC field experiences?

Answer 13

No current

Question 14

Remmeber ti defibrillator difference. Egged. Age rich and electro field path

Answer 14

MAGENTIC decipher cieuclwr, elector parabolic

Question 15

How does oscilloscope work

Answer 15

Time base hoxirntwl in s /cm
V vertical

Z easier peak to peak in oscilloscopes makes it easier

Question 16

Remember that series batteries

Answer 16

Bath resistance and voltsge join

Question 17

Transverse waves

Kogntifunal

Answer 17

All em
Waves on water
S waves earthquake

Sound wave s
Spring
P waves

Longtifunal waves already limited to one plane so can’t be polarise d

Diffraction wavelength doesn’t change but refraction if it went more dense then slows down so wvskentgh closer etc

Question 18

Intensity = powe / area where are 4 oinr5

Answer 18

Itneekty ororptinsly to amplitude 2,

So when’s olitufr form to 9 superposition, so will intensity

Aerials can take differnt polarised waves by aligning so that less itjerefecne between waves will halogen form multiple statins

Question 19

N = c/v

Answer 19

I meant if greater than critical angle it stays in vice Verca

Jessie erefrverice index,
Out light in semi circle so normal ways thst and it refracts across it, measure angle easily, and do itnutnilmirnrrfrscts across edge, then just measure angle sin of ti

Question 20

Principle dof superposition

Answer 20

When two meet the vector addition fo theirndispclsmentd

So if meet in Lahore will supoerpose ti producencinsturuiv eitneferenc emf maximum amplitude and itnneidty thusnicncrewses

But if wnutiohsse constructive

Question 21

Coherence?

Answer 21

Refers to waves having CONSTANR PHASE DIFFERENCE, and thus must have the SAME frequency, phase difference doesn’t have to be same but just constsnt , so thst intefecenc elatterms produced or stable

Question 22

Pld/ wavelen5j x 2pi = phase difference

Answer 22

Here for every 1/2 lambda out, tout of hose,e lambda in lapse etc , from central order 0, we’re there is no path length difference

Question 23

How does young double slit work

Answer 23

Well must come from same route so phase difference is constsnt, gets diffracted through double slit so two sources are produced and they interfere forming patterns

Question 24

Stationary wage

Answer 24

This is where two progressive waves of same frequency travelling in opposite direction supoerpose, where they meet in anti phase destruct to for, w node , where they meet in phase construct to form Antonines

Nice disoslcment always 0

Speewgion between nodes is walkways half thr wwvelenthh

No net energy transfer

Question 25

Difference s

Answer 25

STAIONARY produce no energy net, progressive does Phase difference is thr swme between the nodes , oppsote side is antiphase Wwvelenthh is half Amplitude between all point sin stagikanry same but in stationary maximum at anti etc

Question 26

Sting harmonics

Answer 26

I’d plug then that causes two oroeesive waves of same frewuencyn ti Tavel on each end reflex 190 and thus they supoerpose wnd form a dtaginwry wave Funds,ent frequency is minimum frewuencyn needed Which is fixed for given tensions etc v = f x WL

Question 27

Node one shc side One node and anti node Will be odd Both anti ode, = even

Answer 27

Here it will be internet r,it,impels, so double the frequency half length Odd because always have to add 2/2 extra Can work out by counting total wwvelenthh equation to L

Question 28

Photoelectric effect

Answer 28

Shine photos on metal, providing above work function, electrons will emit So on gold leaf this causes a positive charge to build up and they repel

Question 29

Electrons only emitiredp

Answer 29

1) if incident radiation was above threshold frequency ,so if you increase intensity it wouldn’t increase or even let any electrons be released, which was shocking as original model was that waves were a clot lie bea, of energy 2) last threshold increases intensity, you increase e number if electrons emitted in one to ine tinetevtiodn Increasing rsdisiton Abbie frequency less to electrons releasing with. Or energy

Question 30

Einstein’s

Answer 30

Saudi electron needed a certain amount of energy needed to escape = to the work function , which was the minimum amount of energy needed to escape So if frequency too low, then it would be be able to escape Intersections anooen in one to one Work function means not necaseilly all electrons escape will be from extra energy out in, because some may have higher energies, but this is minimum, so surfsce one’s theoretically should escapement

Question 31

Hf = work + ke max

Answer 31

Max ke becuse e not be easily all will have thid energy Do it sticks witjnjsutnwork function , no energy elft, so So with graph as all rgwduenr same, based in different ttheshiod energies which is x intercept will be trnslsgwe

Question 32

Wave particlmdusliru

Answer 32

Shoes all particles have abe and particle properties Electrons can be diffracted, with dr brig lei wavkentgh = h / momentum Electron wwvelenthh so small so very small selection enered that’s why pilyhcrstslien go white between atoms used Here electron gun to split, and then they diffract and interfere to produce a pattern like waves