Physics

Question 1

Convection

Answer 1

Form of heat transfer where a heated fluid transfers energy by bulk flow and physical motion over another object, or a cooled fluid absorbs energy by the same means.

Question 2

Coulomb’s Law

Answer 2

The law describing the electrostatic force that exists between two charges, q1 and q2.

F = k x q1 x q2 / r ^ 2

Question 3

Current

Answer 3

A flow of charge per time. The flow of charge is motivated by a potential difference (voltage). Current is denoted “i” and can be calculated as Δq / Δt. Current is conventionally considered the theoretical movement of positive charge.

Question 4

Density

Answer 4

A scalar quantity defined as mass per unit volume, often denoted by ρ. Density of an object may be compared to water as a unitless quantity known as specific gravity.

Question 5

Dielectric

Answer 5

An insulating material placed between the two plates of a capacitor; used to increase capacitance. If the circuit is plugged into a current source, more charge will be stored. If the circuit is not plugged in, the voltage of the capacitor will decrease, indirectly increasing its capacitance. The strength of a dielectric is measured by the dielectric constant.

ε = C x d / A x κ

Question 6

Diffraction

Answer 6

The spreading-out effect of light when it passes through a small lit opening.

Question 7

Dispersion

Answer 7

The phenomenon observed when white light is incident on the face of a prism and emerges on the opposite side with all its wavelengths split apart, forming the visible spectrum. This occurs because λ is related to the index of refraction.

n = c / f x λ

Question 8

Displacement

Answer 8

A vector quantity describing the straight-line between an initial and a final position of some particle or object.

Question 9

Doppler effect

Answer 9

When a source emitting a sound and a detector receiving the sound move relative to each other, the perceived frequency f’ is less than or greater than the actual frequency emitted, depending on whether the source and the detector move toward (+) or away (-) from each other.

f’ = f x (v +|- vd) / (v +|- vs).

Question 10

Focal Length

Answer 10

The distance between the focal point and the mirror or lens. For spherical mirrors, the focal length is equal to one-half the radius of curvature.

Question 11

Electric Potential Energy

Answer 11

The amount of work required to bring a test charge q0 from infinity to a point within the electric field of some source charge.

U = q0 x V

Question 12

First Law of Thermodynamics

Answer 12

States that the change in internal energy of a system is equal to the heat transferred into the system minus the work done by the sustem. An extension of the law of conservation of energy.

ΔU = Q - W

Question 13

Exponential Decay

Answer 13

A decrease in the amount of substance N at an exponential rate.

N = N0 x e^-λt

Question 14

Equipotential Lines

Answer 14

Concentric circles emanating from a source charge that cross its electric field lines perpendicularly. No work is required for a test charge to travel along the circumference of an equipotential line because the potential at every point along that line is the same.

Question 15

Electromotive Force

Answer 15

The impetus for current flow created by a voltage source, such as a battery or outlet.

Question 16

Electric Power

Answer 16

The rate at which the energy of flowing charges through a resistor or other device is dissipated.

P = i x V

Question 17

Electromagnetic Waves

Answer 17

When an electric field is changing, it causes a change in a magnetic field and vice-versa, resulting in the propagation of a wave containing an electric and a magnetic field that are perpendicular to each other.

Question 18

Electromagnetic Spectrum

Answer 18

The full range of frequencies and wavelengths for electromagnetic waves broken down into the following regions (in descending order of λ): radio, infrared, visible light, ultraviolet, X-ray, and gamma ray.

Question 19

Electric Potential

Answer 19

The amount of electric potential energy per unit charge; the work required to bring a positive charge q0 from infinity to within an electric field of another positive source charge, Q, divided by that test charge’s magnitude.

v = k x Q/ r

Question 20

Elastic Potential Energy

Answer 20

The energy associated with stretching or compressing a spring, given in the SI unit Joules (J).

U = 1/2 x k x χ^2

Question 21

Electric Field

Answer 21

The electrostatic force that a source charge would exert on a positive test charge: E = F / q0. Electric fields are represented by electric field lines (imaginary lines that show the direction in which a positive test charge is accelerated by the coulombic force due to the electric field of a source charge).