Particles
Give the nuclide notation of deuterium
21H
What is the threshold frequency of a metal?
Q9.2
The frequency of incident radiation below which no photoelectrons are emitted.
Which of the following cannot be polarised? Why?
a) visible light b)sound c) gamma d) infrared
Q13.3
B - sound is longitudinal, waves must be transverse in order to be polarised
Give three safety precautions you should take whilst working with lasers.
Q17.1
Don't shine it at a person / laser safety goggles / avoid shining beam at reflective surface / warning sign / don't look directly into laser / turn off when not needed.
Calculate the specific charge of the nucleus of one Carbon atom
4.79 x 107 C kg-1
Define the electronvolt.
Q10.1
What is the minimum number of polarising filters you could pass unpolarised light through before the light is completely blocked? Explain your answer.
Q13.5
Two - passing light through one causes all light to be polarised in one direction. Another filter aligned perpendicular to the first would block any remaining light.
A stationary wave is created on a string fixed at both ends. The frequency of the first harmonic is 10 Hz, and its wavelength is 3 m.
What is the frequency and wavelength of the third harmonic?
Q15.5
3 x 10 = 30 Hz
first harmonic = 0.5 lambda
length of string / no' of wavelengths = 1 m
An atom of C-14 decays to N via beta-minus decay. Write the balanced nuclear equation for this reaction.
146C --> 147N + 0-1B + anti-electron neutrino
I'm limited here, ok.
The work function of a photocell plate is 4.2 eV. Calculate the max velocity of the emitted photoelectrons.
Q9.4
3.0 x 106 ms-1
State the principle of superposition.
Q14.1
When two or more waves cross, the resultant displacement equals the vector sum of the individual displacements.
A student is using a double slit to investigate interference. Explain why using a laser is better than using a bulb.
Q17.4
Light bulb not coherent and emits light of many wavelengths so no clear interference pattern produced on screen. A laser is coherent and monochromatic so would produce a clear interference pattern.
Calculate the minimum frequency of one of the photons produced when a neutron and anti-neutron annihilate.
2.27 x 1023 Hz
The ground state of an atom = -11.3 eV.
What would happen to the atom if one of its e- in the n=2 state absorbed a photon with 12 eV?
Explain your answer.
Q10.5
Atom would be ionised. An e- in the ground state would need to absorb a minimum of 11.3 eV of energy in order to be removed from the atom. Photon will have enough energy to remove e- in n=2.
An oscillator produces a wave on a string with a speed of 4 ms-1 and a wavelength of 0.8 m.
Two points on the wave have a phase difference of 3060o. Are the points in or out of phase?
Q14.4
Out of phase.
3060 / 360 = 8.5, so the points are 8.5 wavelengths apart, so the points are exactly out of phase.
The light beam from a tunable laser is passed through a diffraction grating of 4.0 x 105 lines per metre.
Calculate the wavelength of the light produced if the angle between the first order maximum and zero order is 16o.
Q18.4
6.9 x 10-7 m
A tau (-ve) lepton decays into a tau-neutrino, an electron anti-neutrino and an electron.
Determine which force causes this interaction, and suggest an exchange particle.
Explain which two other forces it cannot be.
(Q4.7)
Weak nuclear, W+ or W- boson.
Can't be EM as this only affects charged particles (neutrinos not)
Can't be strong nuclear as not hadrons.
Calculate the speed that a neutron would need to be travelling at to have a de Broglie wavelength of 1.8 x 10-10 m.
Q11.5
2.2 x 103 ms-1
Holly lives in a small village in a hilly area. Her house is located several miles from the nearest radio transmitters. Suggest and explain why she is able to tune into the BTunes radio station that uses 945 kHz but not DTunes which transmits at 97.5 MHz.
Q16.6
BT transmits a signal at a much lower f and so longer wavelength - gaps between hills of similar size to BT wavelengths but much larger than DT wavelengths causing BT to diffract more. This means BT wavelengths will be spread out round the hills and reach Holly's radio. DT not diffracted as much so won't spread out and reach Holly.
Compare the similarities and differences between modal and material dispersion in optical fibres. Briefly describe each as part of your answer.
Give one way for each that can reduce the effects of the dispersion.
Q19.4
Both - some light rays take longer to reach the end, pulse broadening.
Modal - caused when light rays enter fibre at different angles so take different paths, so some rays have greater dist to travel.
Material - diff wavelengths travel at diff speeds in the fibre.
Reduce effects - single mode fibre for modal, monochromatic for material.