Exam (elaborations) AQA A Level Physics Paper 3B Astrophysics

, Definition of Principal focus (Focal Point) - CORRECT ANSWERS-The point through
which all light parallel to the axis of the lens passes through

Definition of Focal length - CORRECT ANSWERS-The distance between the centre of
the lens and the focal point.

Formation of images by converging lenses

object beyond 2f - CORRECT ANSWERS-image upside down, small

Formation of images by converging lenses

object between F and lens - CORRECT ANSWERS-image behind lens, upright, small

Ray diagram of a refracting telescope in normal adjustment - CORRECT ANSWERS-

Angular magnification in normal adjustment - CORRECT ANSWERS-Angular
magnification = B/a = fo/fe

B- angle to image
a- angle to object

Cassegrain Telescope - CORRECT ANSWERS-

Definition spherical aberration - lens - CORRECT ANSWERS-Where parallel rays at
different distances from principal axis are brought to focus at different points (on
principal axis). Due to non-parabolic mirror

How to solve spherical aberration - CORRECT ANSWERS-Use a parabolic mirror.

Diagram of spherical aberration of a mirror - CORRECT ANSWERS-rays further from
principal axis are focused to a point closer to mirror

Effect on image of spherical aberration - CORRECT ANSWERS-Image is blurred

Definition chromatic aberration - CORRECT ANSWERS-Where different wavelengths
are refracted by different amounts resulting in different focal lengths for different
wavelengths (colours).

Effect on image of chromatic aberration - CORRECT ANSWERS-Images have
multicoloured, blurred edges

Chromatic aberration - CORRECT ANSWERS-blue light (shorter wavelengths) are
focused closer to lens that red light (longer wavelengths)

Minimum angular resolution