## IB Physics Glossary

 Search full text

 All categories CategoriesAll categoriesNot categorisedTopic 1: Measurements and uncertaintiesTopic 2: MechanicsTopic 3: Thermal PhysicsTopic 4: WavesTopic 5: Electricity and magnetismTopic 6: Circular motion and gravitationTopic 7: Atomic, nuclear and particle physicsTopic 8: Energy productionTopic/AHL 10: FieldsTopic/AHL 11: Electromagnetic inductionTopic/AHL 12: Quantum and nuclear physicsTopic/AHL 9: Wave PhenomenaTopic/Option D: Astrophysics

Page:  1  2  3  4  5  6  7  8  9  10  ...  19  (Next)
ALL

### TOPIC 1: MEASUREMENTS AND UNCERTAINTIES

#### Accuracy

tells us how close the measured value of a quantity is to its true value. An accurate measurement is "close" to a true value. An inaccurate measurement is "far" from a true value.
 Keyword(s): 1.2

#### Derived units

are not fundamental but can be expressed in terms of fundamental units.
 Keyword(s): 1.2

#### Fundamental units

are the most basic units which cannot be expressed in terms of other units. The seven fundamental units are
1. meter (m);
2. second (s);
3. kilogram (kg);
4. Kelvin (K);
5. The Ampere (A);
6. mole (mol);
7. candela (cd).
 Keyword(s): 1.2

#### Log-log plots

are used to find the value of the exponent $n$ and coefficient $a$ for the general relationship $y= a x^n$.
The value of the gradient for the log-log plot equals $n$ and $a= log^{-1}{(\text{y-intercept})}$.
For example
A linear relationship should have $n \approx 1$;
A square-root relationship should have $n \approx \frac{1}{2}$;
A quadratic relationship should have value $n \approx 2$;
An inverse-square relationship should have value $n \approx -2$.
 Keyword(s): 1.2

#### Precision

tells us how consistent repeated measurements are. A precise set of measurements are relatively closer together. An imprecise set of measurements are spread apart.
 Keyword(s): 1.2

#### Proportional relationship

$y \propto x$ or $y = m x$, occurs when the relationship between $y$ and $x$ is linear with a zero y-intercept value, that is, a straight line passing through the origin.
The x- and y-error bars may allow a range of values for the y-intercept, because the lines of max & min gradients, thus showing a possible proportional relationship for a best-fit straight line even if its y-intercept value is non-zero. Beware, for the IB, a best-fit line can be any curve which fits the data points. It does not mean the best-fit straight line.
 Keyword(s): 1.2

#### Random error

is a fluctuating error often present in experiments. It is linked to precision: imprecise data => "high" random error; precise data => "low" random error. Repeated measurements do reduce random errors. Sources of random errors can include varying reading/human error and other randomly flucuating factors which cannot be controlled during experiments.
 Keyword(s): 1.2

#### Scalar multiplication

of vectors, changes the magnitude of the vector but not the direction.
For scalar $a$ and vector $\vec{A}$ with
x- or horizontal component $A_H=A \cos \theta$
y- or vertical compnonet $A_V= A \sin \theta$
magnitude $A=\sqrt{A_H^2 + A_V^2}$

The multiplication $a \times \vec{A}$ has magnitude $a \times A$.
The division $\vec{A} \div a$ has magnitude $A \div a$.
 Keyword(s): 1.3

#### Scalar quantities

have magnitude only. Direction or changes in direction have no effect on scalar quantities. Examples include distance, speed, mass and temperature.
 Keyword(s): 1.3

#### Signifiant figures

a rule, the number of significant digits in a result should not exceed that
of the least precise value upon which it depends.
 Keyword(s): 1.2

Page:  1  2  3  4  5  6  7  8  9  10  ...  19  (Next)
ALL