Cambodia Bac II Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Quadratic formula

For ax²+bx+c=0 with a≠0, x = [-b ± √(b²−4ac)]/(2a). The discriminant b²−4ac determines real, repeated, or complex roots.

Derivative of sin x

The derivative of sin x with respect to x is cos x; this holds when x is measured in radians.

Definite integral

If F is an antiderivative of f, then ∫_a^b f(x) dx = F(b) − F(a). It gives signed area under the curve.

Limit sin x over x

As x approaches 0, sin x / x approaches 1. This limit is used to derive the derivative of sine.

Probability union rule

For events A and B, P(A∪B)=P(A)+P(B)−P(A∩B). Subtract the intersection so outcomes counted twice are corrected.

Geometric sequence nth term

For first term a and common ratio r, the nth term is a r^(n−1). The sum of n terms is a(1−r^n)/(1−r) for r≠1.

Newton's second law

The net force on an object equals its mass times acceleration: ΣF = ma. Force and acceleration point in the same direction.

Ohm's law

For a conductor at constant temperature, V = IR. Voltage equals current times resistance; resistance is in ohms.

Wave equation

Wave speed equals frequency times wavelength: v = fλ. Frequency is in hertz and wavelength in metres.

Snell's law

For light crossing a boundary, n₁ sin θ₁ = n₂ sin θ₂. Angles are measured from the normal, and n = c/v.

Half-life

After one half-life, half of a radioactive sample remains. The number remaining after time t is N = N₀ e^(−λt), with T½ = ln2/λ.

Ideal gas law

For an ideal gas, PV = nRT. Pressure times volume equals moles times the gas constant times absolute temperature.

Mole formula

The number of moles equals mass divided by molar mass: n = m/M. One mole contains Avogadro's number, about 6.02×10²³ particles.

Molarity

Molarity is moles of solute per litre of solution: M = n/V. Dilution obeys C₁V₁ = C₂V₂.

pH definition

pH = −log₁₀[H⁺]. At 25 °C, pH + pOH = 14; pH below 7 is acidic, above 7 is basic.

Oxidation and reduction

Oxidation is loss of electrons; reduction is gain of electrons. In a redox reaction, the two processes occur together.

Periodic atomic radius trend

Atomic radius decreases across a period from left to right and increases down a group. This reflects effective nuclear charge and shell number.

Carboxylic acid group

Carboxylic acids contain the −COOH group. They are weak acids that donate the hydrogen from the hydroxyl part of the group.

Photosynthesis equation

Photosynthesis converts carbon dioxide and water into glucose and oxygen using light energy: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. It occurs in chloroplasts.

Cellular respiration

Aerobic respiration releases energy from glucose: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP. Most ATP is produced in mitochondria.

DNA base pairing

In DNA, adenine pairs with thymine and guanine pairs with cytosine. The two strands are antiparallel and held by hydrogen bonds.

Mitosis versus meiosis

Mitosis produces two genetically identical diploid cells. Meiosis produces four haploid gametes and introduces genetic variation through crossing over and independent assortment.

Law of segregation

Mendel's law of segregation states that the two alleles of a gene separate during gamete formation. Each gamete receives one allele.

Reamker

The Reamker is the Khmer epic adaptation of the Ramayana. Its main characters include Preah Ream, Neang Sita, Preah Leak, Krong Reap, and Hanuman.

Chbap

Chbap are Khmer didactic poems that teach moral conduct. Chbap Pros addresses men, while Chbap Srei addresses women, using aphorisms and metaphors.

Tum Teav

Tum Teav is a classic Khmer tragic love story set in Kampong Cham. The best-known literary version is by Preah Botumthera Som.

Preah Vesandor

Preah Vesandor is a Khmer Buddhist story of the Bodhisattva's final human birth. It teaches Dana, or generosity, and is widely recited in Khmer culture.

Phka Srabon

Phka Srabon, or Wilted Flower, is a Khmer novel by Nou Hach. It explores love and social constraints in twentieth-century Cambodia.

Present perfect

The present perfect is formed with have or has plus the past participle. It links a past action to the present, often with since, for, already, or yet.

Second conditional

The second conditional uses if + past simple, then would + base verb. It describes unreal or unlikely present or future situations.

Passive voice

The passive voice is formed with be plus the past participle. The object becomes the subject, and the agent can be introduced with by.

Comparative adjectives

Short adjectives form the comparative with -er and the superlative with -est. Long adjectives use more and most; good becomes better and best.