Scottish Advanced Higher Physics Flashcards

24 sample cards from the Physics deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What is the energy of a photon of frequency $f$ (or wavelength $\lambda$)?

   $E = hf = \frac{hc}{\lambda}$, where $h = 6.63 \times 10^{-34}$ J s.

2. Describe quantum tunnelling.

   A quantum particle has a finite probability of passing through a potential barrier higher than its energy, because its wavefunction extends into and beyond the barrier — impossible in classical physics.

3. What are cosmic rays and what are they primarily composed of?

   High-energy charged particles from space, mostly protons (about 89%) and alpha particles (about 10%), with a small fraction of heavier nuclei and electrons.

4. How does the geomagnetic field affect charged cosmic-ray particles approaching Earth?

   The magnetic field exerts a force $F = qvB\sin\theta$, deflecting charged particles toward the magnetic poles and trapping some in the Van Allen radiation belts.

5. Define simple harmonic motion (SHM) and give its defining equation.

   Motion where acceleration is proportional to displacement and directed toward equilibrium: $a = -\omega^{2}y$.

6. Give the SHM solutions for displacement starting from (a) the equilibrium and (b) maximum displacement.

   (a) $y = A\sin(\omega t)$; (b) $y = A\cos(\omega t)$, where $A$ is the amplitude.

7. State the SHM expression for velocity as a function of displacement, and its maximum value.

   $v = \pm\omega\sqrt{A^{2} - y^{2}}$; maximum at $y = 0$ giving $v_{\max} = \omega A$.

8. Give the kinetic and potential energy expressions in SHM.

   $E_{k} = \frac{1}{2}m\omega^{2}(A^{2} - y^{2})$ and $E_{p} = \frac{1}{2}m\omega^{2}y^{2}$; total energy $= \frac{1}{2}m\omega^{2}A^{2}$.

9. Describe the difference between underdamping, critical damping and overdamping.

   Underdamping: oscillates with decaying amplitude. Critical damping: returns to equilibrium fastest without oscillating. Overdamping: returns to equilibrium slowly without oscillating.

10. Write the general equation of a travelling wave.

    $y = A\sin 2\pi\!\left(ft - \frac{x}{\lambda}\right)$, equivalently $y = A\sin(\omega t - kx)$ with $k = \frac{2\pi}{\lambda}$.

11. Define phase difference between two points a distance $\Delta x$ apart on a wave.

    $\phi = \frac{2\pi \Delta x}{\lambda}$ (radians).

12. State the condition for constructive and destructive interference in terms of path difference.

    Constructive: path difference $= m\lambda$. Destructive: path difference $= (m + \tfrac{1}{2})\lambda$, for integer $m$.

13. Give the diffraction-grating equation.

    $d\sin\theta = m\lambda$, where $d$ is the slit separation, $\theta$ the angle to the $m$-th order maximum, and $m$ an integer.

14. What condition produces a phase change on reflection, relevant to thin-film interference?

    A phase change of $\pi$ (half a wavelength) occurs when a wave reflects off a medium of higher refractive index; no phase change off a lower-index medium.

15. State Coulomb's law for the force between two point charges.

    $F = \frac{Q_{1}Q_{2}}{4\pi\varepsilon_{0} r^{2}}$, with $\varepsilon_{0} = 8.85 \times 10^{-12}$ F m$^{-1}$.

16. Give the electric field strength and electric potential of a point charge $Q$.

    $E = \frac{Q}{4\pi\varepsilon_{0} r^{2}}$ (N C$^{-1}$) and $V = \frac{Q}{4\pi\varepsilon_{0} r}$ (V).

17. Relate electric field strength to potential gradient, and give the field between parallel plates.

    $E = -\frac{dV}{dr}$. For uniform parallel plates, $E = \frac{V}{d}$.

18. What is the energy gained by a charge $q$ accelerated through a potential difference $V$, and the resulting speed?

    $E_{k} = qV$, so $\frac{1}{2}mv^{2} = qV$ giving $v = \sqrt{\frac{2qV}{m}}$ (non-relativistic).

19. Define capacitance and give the energy stored in a capacitor.

    $C = \frac{Q}{V}$ (farads). Energy stored $= \frac{1}{2}QV = \frac{1}{2}CV^{2} = \frac{Q^{2}}{2C}$.

20. Give the charging equations for a capacitor in an RC circuit (time constant).

    Charging: $V_{C} = V_{0}(1 - e^{-t/RC})$ and $I = I_{0}e^{-t/RC}$. Time constant $\tau = RC$.

21. State the force on a current-carrying conductor and on a moving charge in a magnetic field.

    Conductor: $F = BIL\sin\theta$. Moving charge: $F = qvB\sin\theta$.

22. Give the magnetic flux density at distance $r$ from a long straight current-carrying wire.

    $B = \frac{\mu_{0} I}{2\pi r}$, where $\mu_{0} = 4\pi \times 10^{-7}$ H m$^{-1}$ (T m A$^{-1}$).

23. State Faraday's law and Lenz's law of electromagnetic induction.

    Faraday: induced EMF $\varepsilon = -N\frac{d\Phi}{dt}$. Lenz: the induced current opposes the change in flux producing it (the negative sign).

24. How is the absolute uncertainty in a result combined when quantities are multiplied or divided?

    Add the fractional (percentage) uncertainties in quadrature: $\frac{\Delta Z}{Z} = \sqrt{\left(\frac{\Delta a}{a}\right)^{2} + \left(\frac{\Delta b}{b}\right)^{2}}$; for addition/subtraction add absolute uncertainties in quadrature: $\Delta Z = \sqrt{(\Delta a)^{2} + (\Delta b)^{2}}$.

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