Paper 1 - Weak Points

Question 1

What interaction produces strange particles?

Answer 1

The strong interaction

Question 2

What interaction do strange particles decay through?

Answer 2

The weak interaction

Question 3

T/F: EM waves travel at different speeds in a vacuum dependent on their wavelength

Answer 3

False: all EM waves travel at the same speed in a vacuum

Question 4

Define polarisation

Answer 4

The process of restricting the oscillations of particles in a transverse wave to one plane that is still perpendicular to the direction of wave propagation or energy transfer

Question 5

Why can polarisation only take place in traverse waves?

Answer 5

Particles cannot oscillate in more than one plane in longitudinal waves because they have to oscillate parallel to the direction of wave propagation or energy transfer

Question 6

What are the two directions of polarising a transverse wave?

Answer 6

Vertically or horizontally

Question 7

Why might you see no wave transmitted after polarising it?

Answer 7

Because it only had components in one plane originally and they were both polarised

Question 8

What is plane polarisation?

Answer 8

Another name for polarisation in which the oscillations of particles in a transverse wave are restricted to one plane perpendicular to the direction of wave propagation or energy transfer

Question 9

What do you see if you rotate a polariser through 360 degrees?

Answer 9

Peaks and troughs in the intensity of the wave that looks like a sin curve

Question 10

What happens to the intensity of a polarised wave?

Answer 10

It decreases

Question 11

Which property of a wave changes when it diffracts?

Answer 11

The amplitude

Question 12

How does the amplitude of a diffracted wave change?

Answer 12

The amplitude of the diffracted wave is less than that of the incident wave because the energy is distributed over a wider area

Question 13

Why does diffraction occur?

Answer 13

When a wave passes through an aperture it is forced to curve and this causes it to interfere

Question 14

What does the interference pattern formed by diffraction look like?

Answer 14

The interference pattern has one large and bright central maxima and then several dark fringes that have decreasing intensity on either side of it

Question 15

What does the interference pattern look like if you diffract white light?

Answer 15

There is a central white maxima with a spectrum on either side of it

Question 16

What happens to the interference pattern if you increase the wavelength of light?

Answer 16

You increase the angle of diffraction meaning the interference pattern gets more spread out, the fringes get wider and dimmer so fewer maxima can be seen

Question 17

T/F: Increasing the wavelength has the same effect on the interference pattern as decreasing the slit width in diffraction

Answer 17

True

Question 18

What is material dispersion?

Answer 18

When different wavelengths of light take different amounts of time to travel through the optical fibre because they travel at different speeds in the core

Question 19

What does material dispersion cause?

Answer 19

Signal degradation and pulse broadening

Question 20

What is model dispersion?

Answer 20

When different waves take different paths through the core meaning they arrive at the other end of the optical fibre at different times

Question 21

What does modal dispersion cause?

Answer 21

Signal degradation and pulse broadening

Question 22

What is the solution to material dispersion?

Answer 22

Use a monochromatic light source

Question 23

What is the solution to modal dispersion?

Answer 23

Use a step index core

Question 24

What is absorption in a fibre optic cable?

Answer 24

When the signal is absorbed by the materal

Question 25

Why is absorption a problem for transmitting information via fibre optic cables?

Answer 25

Absorption causes a reduction in amplitude of the signal meaning it can be misinterpreted and this causes signal degradation

Question 26

What is the solution to signal degradation?

Answer 26

Use repeaters to boost the signal

Question 27

Define projectile motion

Answer 27

When an object experiences motion in the vertical and horizontal planes in a uniform gravitational field

Question 28

Define elastic deformation

Answer 28

Deformation of a material that will allow it to return to its original shape after the load has been removed

Question 29

Define plastic deformation

Answer 29

Deformation of a material that will not allow it to return to its original shape after the load has been removed

Question 30

What is the name for the linear section of a force-extension graph?

Answer 30

The elastic region

Question 31

What is the name for the curved section of a force-extension graph?

Answer 31

The plastic region

Question 32

What is the limit of proportionality?

Answer 32

The point where a material stops obeying Hooke's Law

Question 33

How can we see the limit of proportionality on a force-extension graph?

Answer 33

The graph stops being linear

Question 34

What is the elastic limit?

Answer 34

The point at which the material stops elastically deforming and starts plastically deforming

Question 35

Define brittle material

Answer 35

Materials that have little to no plastic region and reach their breaking point with little to no deformation

Question 36

Define ductile material

Answer 36

Materials that have a large plastic region meaning they reach their breaking point after a large amount of plastic deformation

Question 37

What does the I-V graph look like for an ohmic conductor?

Answer 37

A linear graph

Question 38

What does the I-V graph look like for a semiconductor diode?

Answer 38

y = x^3, with an point of inflection at 0

Question 39

What does the I-V graph look like for a filament lamp?

Answer 39

A logarithmic graph in both positive and negative y

Question 40

What happens to the resistance of a thermistor when the temperature increases?

Answer 40

The resistance increase

Question 41

What happens to the resistance of an LDR when the light intensity increases?

Answer 41

The resistance decreases

Question 42

What is superconductivity?

Answer 42

A property of some materials where they have zero resistivity below a critical temperature

Question 43

How do you determine the critical temperature for a superconductor?

Answer 43

It is dependent on the material

Question 44

Why do we use potential dividers?

Answer 44

They provide an output voltage that is a fraction of the input voltage

Question 45

Define emf

Answer 45

The amount of chemical energy that is converted to electrical energy and transferred to a coulomb of charge when it passes through the power supply

Question 46

Define lost volts

Answer 46

The difference between the potential difference supplied to the circuit and the emf of the cell that is due to the work done against the internal resistance of the power supply

Question 47

What two conditions do you need for Young's Double Slit experiment to be able to accurately determine the wavelength?

Answer 47

The screen distance must be much greater than the slit width The path difference must be greater than half a wavelength