Physics Compendium for Biomedical Engineering

Flashcards generated from Physics Compendium for Biomedical Engineering lecture notes.

What is a physical quantity?

A measurable aspect of a physical phenomenon, expressible as a numerical value with a unit.

What are the fundamental physical quantities?

Length (m), Mass (kg), Time (s), Temperature (K), Electric current (A).

What are examples of derived physical quantities?

Velocity (m/s), Force (N), Energy (J), Pressure (Pa).

What is a physical model?

A simplified but effective representation of how nature behaves.

What are some examples of physical models?

Newton’s Laws, Ideal Gas Law, Bohr’s atom.

What is a limitation of physical models?

Every model has a boundary.

Give an example where Newtonian mechanics fails.

Newton’s mechanics fails at very high speeds.

What is a rule for operations on physical quantities?

Add/subtract same types only.

Give an example of how multiplication/division creates new units.

Speed = Distance / Time.

What happens when multiplying a scalar and a vector?

Scales its magnitude.

What conclusion can be drawn from observing that it gets hotter when rubbing hands?

Friction increases thermal energy.

Give examples of scalar quantities.

Mass, Temperature, Energy.

Give examples of vector quantities.

Force, Acceleration, Electric field.

What is a graphical tip for representing vectors?

Use arrows to represent vectors. Longer arrows = greater magnitude.

What is the basic concept of the Bohr Model of the atom?

Electrons orbit the nucleus in discrete energy levels.

What is the key feature of the Quantum Model of the atom?

Orbitals describe probability clouds; electrons are smeared, not points.

What is the band structure of a conductor?

Valence and conduction bands overlap.

What is the band structure of an insulator?

Large band gap.

What is the band structure of a semiconductor?

Small band gap, tunable with doping.

What happens during absorption in terms of energy levels?

Electron jumps up a level by absorbing energy.

What happens during emission in terms of energy levels?

Falls down a level, emits a photon.

What characterizes conductors in terms of electrons?

Free electrons (e.g., Cu, Al).

What characterizes insulators in terms of electrons?

Bound electrons (e.g., glass).

How can semiconductors switch conductivity?

Switch from insulators to conductors via temperature or doping.

What characterizes n-type semiconductors?

Extra electrons (from dopants like P).

What characterizes p-type semiconductors?

Missing electrons or “holes” (from B).

What happens at a PN junction?

Barrier forms between p and n regions — crucial in diodes and transistors.

What is the molecular model of gases?

Kinetic theory describes gases as countless moving particles.

According to kinetic theory, what is pressure proportional to?

Proportional to collision frequency × momentum.

What is temperature (in the context of thermodynamics)?

Average kinetic energy of molecules.

What is pressure (in the context of thermodynamics)?

Force molecules exert on container walls per unit area.

What is the equation for pressure?

P = F / A

What are the characteristics of a solid?

Fixed shape, low energy.

What are the characteristics of a liquid?

Takes container shape, higher energy.

What are the characteristics of a gas?

Free motion, fills volume.

What is plasma?

Ionized gas with extreme energy.

What is the Zeroth Law of Thermodynamics?

A = B and B = C implies A = C — basis of thermometers.

What is the First Law of Thermodynamics?

Energy conservation. ∆U = Q + W.

What is the Second Law of Thermodynamics?

Heat flows spontaneously from hot to cold; entropy increases.

What is the Third Law of Thermodynamics?

You can’t reach 0 K in finite steps.

What is the Ideal Gas Equation?

pV = nRT

How does temperature affect wavelengths in blackbody radiation?

Hotter objects emit more energy at shorter wavelengths (shift toward blue).

What is an electric field?

A region where a charge feels a force. Arrows point from + to -.

What is a key characteristic of a magnetic field?

Magnetic field affects moving charges only.

What is the Lorentz Force equation?

F⃗ = q(E⃗ + ⃗v × B⃗ )

What did Maxwell's equations reveal about EM waves?

EM waves are self-propagating fields.

What is the speed of light according to Maxwell's equations?

c = 1 / sqrt(µ0ε0)

What is the transverse nature of electromagnetic waves?

E⃗ and B⃗ are perpendicular to each other and to propagation direction.

What are the different types of EM radiation?

Radio, Microwave, Infrared, Visible, UV, X-rays, Gamma.

What is the safety concern with ionizing radiation?

Ionizing radiation (UV, X-rays, γ) can break molecular bonds — handled with shielding.