Thermodynamics, Electromagnetism, Optics & Nuclear Physics: Key Concepts and Formulas

What is the definition of heat?

The energy transferred between systems or objects with different temperatures (thermal energy in transit).

What is the formula for temperature change?

Q=mcΔT

What is the formula for phase change?

Q=mL

True or False: During a phase change, energy goes into changing kinetic energy (temperature).

False. Energy goes into breaking or forming intermolecular bonds.

What is latent heat of fusion (Lf)?

Energy per unit mass required to change a substance from solid to liquid.

What is latent heat of vaporization (Lv)?

Energy per unit mass required to change a substance from liquid to gas.

Is the change in temperature (ΔT) different in Celsius and Kelvin scales?

No. Since the size of one degree Celsius is equal to one Kelvin, ΔT is the same in both scales.

What is the sign convention for heat (Q) in thermodynamics?

Positive (+) if heat flows into the system; Negative (-) if heat flows out.

What is the sign convention for work (W) in thermodynamics?

Positive (+) if work is done by the system (expansion); Negative (-) if work is done on the system (compression).

In which direction does heat flow spontaneously?

From an object at a higher temperature to an object at a lower temperature.

What temperature scale must be used for Carnot efficiency calculations?

The Kelvin scale.

How do like and opposite charges interact?

Like charges repel, and opposite charges attract.

What is the direction of an electric field relative to positive and negative charges?

It points away from positive charges and toward negative charges.

How does a positive charge move in an electric field?

It experiences a force in the same direction as the electric field.

How does a negative charge move in an electric field?

It experiences a force in the opposite direction of the electric field.

What happens to electric potential as you move with the field?

It decreases.

In which direction do positive charges accelerate in terms of potential?

They accelerate toward decreasing potential (downhill).

In which direction do negative charges accelerate in terms of potential?

They accelerate toward increasing potential (uphill).

What is the Right Hand Rule for magnetic force on a positive charge?

Point fingers in the direction of velocity (v), curl them toward the magnetic field (B); the thumb points in the direction of the force (F).

What are the three factors that change magnetic flux?

Change in magnetic field strength (B), change in area of the loop (A), or change in the angle (θ) between them.

What does Lenz's Law state?

The induced current creates a magnetic field that opposes the change in magnetic flux that produced it.

What is the thin lens equation?

1/f = 1/do + 1/di

What is the formula for magnification?

m = -di/do = hi/ho

What is the normal near point and far point for human vision?

Near point is 25 cm; Far point is infinity (∞).

What type of lens is used to correct nearsightedness?

Diverging (concave) lens.

What type of lens is used to correct farsightedness?

Converging (convex) lens.

What is an alpha particle?

A helium nucleus consisting of 2 protons and 2 neutrons.

What is a beta-minus particle?

An electron ejected from the nucleus.

What is a gamma ray?

A high-energy photon (light).

What is the definition of half-life?

The time required for half of the radioactive nuclei in a sample to decay.

What is the path length difference for constructive interference?

The path length difference must be an integer multiple of the wavelength, expressed as ΔL = mλ, where m = 0, 1, 2, ...

What is the path length difference for destructive interference?

The path length difference must be an odd half-integer multiple of the wavelength, expressed as ΔL = (m + 0.5)λ, where m = 0, 1, 2, ...

For the two-slit experiment, which fringes are constructive interference and which are destructive interference?

Constructive interference results in bright fringes (maxima), while destructive interference results in dark fringes (minima).

When using the small-angle approximation in the two-slit experiment, what angular measure must be used?

You must use radians, not degrees, for the small-angle approximation (sin θ ≈ θ) to be valid.

What is the small-angle approximation formula for the position of bright fringes in a two-slit experiment?

The position y of the m-th bright fringe is given by y = (mλL) / d, where λ is the wavelength, L is the distance to the screen, and d is the slit separation.

What are the three questions to determine the direction of induced current in a loop?

1. Is the magnetic flux changing? 2. Is the magnetic flux increasing or decreasing? 3. What is the direction of the magnetic field produced by the induced current to oppose the change in flux?

What three things can change the magnetic flux through a loop?

1. Changing the magnitude of the magnetic field, 2. Changing the area of the loop, 3. Changing the angle between the magnetic field vector and the area vector.

The equivalent capacitance of a set of parallel capacitors is always _______ than the largest individual capacitance.

Greater

The equivalent capacitance of a set of series capacitors is always ______ than the smallest individual capacitance.

Smaller

Series capacitors all have the same:

Charge

Parallel capacitors all have the same:

Voltage

As you add more resistors to a series circuit, what happens to the equivalent resistance?

The equivalent resistance increases.

The current in series resistors is _________ for all resistors; the voltage drop across each resistor depends on _________.

The same; the individual resistance of each resistor.

The equivalent resistance of a set of series resistors is always _________ than the largest resistance.

Greater

As you add more resistors to a parallel circuit, what happens to the equivalent resistance?

The equivalent resistance decreases.

The voltage across each resistor of a parallel circuit is ____________; the current through each resistor depends on ___________.

The same; the individual resistance of each resistor.

The equivalent resistance of a set of parallel resistors is always _________ than the smallest resistance.

Smaller

When analyzing combination circuits, resistors in parallel all have the same _________ and resistors in series all have the same _________.

Voltage; current

In the formula for the magnetic force on a charged particle (F = qvB sinθ), what is the angle θ measured between?

The angle between the velocity vector of the particle and the magnetic field vector.

The magnetic force vector is always __________ to both the magnetic field vector and the velocity vector.

Perpendicular

If a tree dies at 100 years old and is found 1000 years later, how old will Carbon-14 dating say the tree is?

The tree will be dated as 1000 years old, as Carbon-14 dating measures the time elapsed since the organism died (when it stopped exchanging carbon with the environment).

What happens in alpha decay?

An unstable nucleus emits an alpha particle (a helium nucleus consisting of 2 protons and 2 neutrons), reducing the atomic number by 2 and the mass number by 4.

What happens in beta-minus decay?

A neutron in the nucleus turns into a proton, emitting an electron (beta particle) and an antineutrino, increasing the atomic number by 1 while the mass number remains the same.

What happens in gamma decay?

An excited nucleus releases excess energy by emitting a high-energy gamma-ray photon, without changing the number of protons or neutrons.

Angle in Magnetic Force Formula

The angle between the velocity vector of the particle and the magnetic field vector.

for combo of lens, image produced by one is _____ for the next

object

how does far point change for nearshighted person

decreases from infinity

how does near point change for farsighted person

increases

When correcting for nearsightedness, you want to take an object at the person’s far point at and make an image at _________

far point

When correcting for farsightedness, you want to take an object near the person’s eye (say 25 cm away) and make an image at

actual near point