PPQ Corrections Flashcards
The peak wavelength of radiation is _______ for hotter objects.
shorter
The rate of radiation emitted is _______ for hotter objects.
greater
What does the graph that shows the relationship between frequency and wavelength of photons of radiation look like?
standard curve with negative gradient
What happens to the speed and the wavelength of a ray of light when it goes from water to air?
Both increase
Tension = …
Force + FRICTION
What happens to the tension when friction is increased?
Tension increases.
Unbalanced force remains the same.
What do airbags do?
Increase the time of contact the driver has with the steering wheel.
This reduces the force experienced by the driver.
A light will only turn on when the pn junction is _______ bias.
forward
What’s the difference between photons emitted by blue LED and photons emitted by red LED?
Blue has a larger band gap.
Photons of blue light have more energy.
Photons emitted by blue light have a shorter wavelength.
What is the fundamental force associated with beta decay.
Weak nuclear force.
Why is alternating voltage used in the cyclotron.
To ensure the electric field is always in the correct direction.
Hand trick:
Thumb: Current
Pointer: Magnetic field
Middle: Force (out of page)
Explain how a line emission spectrum is produced:
If an electron is in an excited state it can return to a lower energy level. When it does this, it emits a photon.
Different transitions produce different lines (frequencies of photons).
Why are some lines on the emission spectrum brighter than others?
More electrons are making those transitions per second.
Therefore, there are more photons of that specific energy emitted and produce brighter lines.
What is a critical angle?
The angle of incidence that produces an angle of refraction of 90°.
What effect does increasing total resistance have on the power dissipated by internal resistance?
Increasing total resistance decreases power dissipated by internal resistance.
This is due to the current being decreased by increased resistance.
Absolute uncertainty
Take the highest % uncertainty of products.
Times that by the answer.
Suggest an improvement to any experiment…
Repeat the measurements and take the mean.
Force parallel to the slope
mgsinθ
Fermions
Family of particles made up of quarks and leptons
The two types of quark are
Baryons (3 quarks)
Mesons (quark and antiquark)
Leptons consist of
Electron
Muon
Tau
Neutrinos
Hadrons
Held together by the strong force
E.g baryons and mesons
As a capacitor charges the current…
Decreases
Potential difference across a resistor _________ as capacitor charges
Decreases
What effect does reducing velocity have on the maximum height reached?
Reducing velocity reduces the INITIAL VERTICAL VELOCITY decreasing the maximum height reached.
Interaction is elastic when…
TOTAL Ek before = TOTAL Ek after
Photovoltaic Effect
When photons of light are incident on a photodiode (e.g pn junctions) it produces a potential difference.
How is a potential difference produced when photons of light are incident on a photodiode?
Photons hit pn junction which moves electrons up into conduction band removing the depletion layer, causing a current.
Why are protons accelerated in an electric field?
Protons are positively charged.
Protons experience a force in the electric field.
What happens to the speed of a proton in an electric field when the distance it travels is increased?
No effect since work done is the same.
Why would a setup not be suitable for investigating inverse square law?
Setup is not a point source.
Define the term ‘coherent’
Waves have a constant phase relationship.
What is emf?
The energy gained by 1 coulomb of charge passing
through the battery.
E=IR+Ir can be rewritten as…
emf = t.p.d + lost volts
When asked how to take emf reading from a setup say…
Reading on the voltmeter before the switch is closed.
What is conserved in an elastic collision?
Total momentum
Total energy
Total kinetic energy
What happens to the wavelength on the screen when timebase is halved.
It is doubled.
System uncertainties occur when…
Measurements are either all smaller or all larger than the true value of the quantity.
How does quartering mass affect the gravitational force of attraction?
Quarters it.
How does halving the distance between objects affect the gravitational force of attraction?
Makes it 4x larger.
Vertical tension(Tv)=
Tcosθ
What happens to tension when angle is increased.
Decreases since the cosine of the angle decreases.
When adding a line to a graph showing how energy emitted per second varies with wavelength for a HOTTER star
Make sure the line is always above the cooler stars line.
Describe how apparatus can be used to verify inverse square law.
Obtain values of irradiance for
different distances.
Determine I × d^2
Values of Id^2 should be constant.
Why does light with a shorter wavelength produce a smaller angle between central and first maxima?
The path difference is smaller therefore the spots are closer together.
What effect does the slit separation have on the angle between central and first maxima?
Larger slit separation produces a smaller angle which is more difficult to measure.
Greater refractive index causes ____ internal reflection.
more
Why does voltage decrease when a circuit with a resistor is connected.
When the circuit connects a current flows through it causing volts to be lost across the resistor.
When a lift accelerates downwards the reading on the scale will be
A CONSTANT value less than the true weight.
Name the 6 quark types
up/down
top/bottom
charm/strange
The right hand rule is only for…
Negative particles
What happens to the frequency of a ray of light when it goes from air to water?
Remains unchanged.
What effect does reducing irradiance have on the kinetic energy of the photoelectrons ejected from the metal?
No change since irradiance does not affect the energy of the photons.
Explain why the photoelectric effect provides evidence for the particle nature of light.
Each photon removes one electron.
Total internal reflection occurs when…
The angle of incidence is greater than the critical angle.
A prism with a lower refractive index will have…
A spectrum with less dispersion.
2 features of the Bohr model:
A positively charged nucleus.
Electrons in shells orbiting the nucleus.
