Y1 Past Paper Corrections

Question 1

Key terminology with waves

Answer 1

• Use the term ‘oscillations’

Question 1

Relationship between wave intensity and amplitude

Answer 1

I ∝ A^2

Question 2

Wavelength definition

Answer 2

The minimum distance between two adjacent points oscillating in phase, e.g. distance between two peaks/compressions.

Question 3

State the principle of superposition

Answer 3

When two or more waves meet at a point, the resultant displacement at that point is equal to the sum of the displacements of the individual waves.

Question 4

What happens to fringe separation if distance slits in double-slit experiment increases?

Answer 4

λ = ax / D
a = distance between slits
x = fringe separation
D = slits to screen distance

• D is constant, λ is constant
• If a increases, X decreases.

Question 5

Show W = VQ can be written in base untis

Answer 5

V = W/Q
W = N x D
W = kg ms-2 x D
Q = As
now divide the top by buttom

Question 6

SI units

Answer 6

• metre (m)
• kilogram (kg)
• second (s)
• ampere (A)
• kelvin (K)
• mole (mol),

Question 7

prefixes below 10^1 metres

Answer 7

deci -1
centi -2
milli -3
pico -12
femto -15

Question 8

Units expressed in other SI units

Answer 8

N = kg ms-2
Pa = Nm-2
J = Nm
W = J s-1
V = J C-1
Ohm = V A-1
C = A s
Hz = s-1

Question 9

Remember for calculating voltage/resistance when 2 components are invovled

Answer 9

V1 / V2 = R1 / R2

Question 10

How to measure diameter

Answer 10

• Vernier callipers, repeat measurements ALONG object.

Question 11

Why is it useful to make sure metal contacts used to complete a circuit are large?

Answer 11

To ensure the entire CSA of the conductor is in contact with the contacts.

Question 12

Formula to calculate cross sectional area, and device

Answer 12

• Use a micrometre in multiple places, take average if needed, then πd^2 / 4

Question 13

Practical to find breaking stress of wire

Answer 13

• Method of fixing wire and load at other end.
• Safety (eyes and floor with sand).
• Measure masses.
• Measure diameter (micrometre), take average, repeat.
• Calculate force mg, and CSA
• Breaking stress = max force / CSA

Question 14

Practical to find Young’s Modulus of wire

Answer 14

• Method of fixing wire and load at other end.
• Safety (eyes and floor with sand).
• Measure masses.
• Measure diameter (micrometre), take average, repeat.
• Calculate force mg, and CSA
• Graph mg/N against e/M, gradient = e/mg
• Young’s modulus = mgL / Ae, now L / A x Gradient

Question 15

Stress/strain graph for loading/unloading on glass and rubber

Answer 15

• Glass is a straight line through the origin
• Rubber extension starts slow, then gets much larger, then slows. Gradient high, flattens, high.

Question 16

Formula to find speed of electron in electron gun

Answer 16

eV = 1/2 mv^2
v = √(2eV / m)

Question 17

Relationship between de broglie wavelength and p.d

Answer 17

λ ∝ 1 / √V
If p.d increases de Broglie wavelength decreases, pattern becomes smaller.

Question 18

de Broglie wavelength formulas

Answer 18

λ = h / p
v = √(2eV / m)

Question 19

Explain why a ball falling from rest follows the conservation of momentum

Answer 19

The earth is part of the closed system. The earth has opposite momentum to falling ball, and moves upward. Albeit by a tiny speed, as its mass is so large.

Question 20

Define Interference

Answer 20

The superposition of coherent waves. The waves can superpose constructively or destructively.

Question 21

Relationship between resistance per unit length of wire r, and diameter D

Answer 21

r = 1/D^2

Question 22

What is refractive index

Answer 22

Speed of light in vacuum / speed of light in material

Question 23

How is momentum related to KE

Answer 23

p= √(2m x KE)

Question 24

relationship between KE and momentum

Answer 24

KE = p^2 / 2m

Question 25

Snell’s Law

Answer 25

The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant.
n1 sinθ1 = n2 sinθ2

Question 26

Formula relating power, force, velocity

Answer 26

P = Fv

Question 27

Impulse formula using force and time

Answer 27

Impulse = F x Change In Time

Question 28

Phase difference to path difference CORRECT

Answer 28

Phase Difference = 2pi x path difference / lambda

Question 29

Wavelength for radiowaves

Answer 29

> 10^6 to 10^-1 (metres)

Question 30

Wavelength for microwaves

Answer 30

10^-1 to 10^-3

Question 31

Wavelength for infrared waves

Answer 31

10^-3 to 7x10^-7

Question 32

Wavelength for visible light

Answer 32

700nm 400nm

Question 33

Wavelength for ultraviolet

Answer 33

4x10^-7 to 10^-8

Question 34

Wavelength for x-rays

Answer 34

10^-8 to 10^-10

Question 35

Wavelength for gamma rays

Answer 35

10^-13 to <10^-16

Question 36

Possible wavelength for gamma and X-ray overlap

Answer 36

10^-10 to 10^-13

Question 37

For a wire, formula related to spring stiffness and the wire’s properties

Answer 37

K = YA/L
stiffness = young’s modulus x CSA / length

Question 38

Volume of sphere

Answer 38

4/3 * π * r^3

Question 39

Relationships between intensity and distance

Answer 39

I ∝ 1/d^2 (intensity inversely proportional to distance squared)

d ∝ 1 / √ I (distance inversely proportional to root intensity)

Question 40

Phase Difference Definition

Answer 40

• Difference in degrees between the same point on two waves

Question 41

Formula relating the power, number of photons emitted, and energy of a single photon

Answer 41

P = N × E

E = λ / hc n