Convex and concave lenses, real and virtual images, magnification, why objects appear coloured, and how black body radiation controls the temperature of the Earth. Physics only content.
You can study this deck without signing up — your progress is kept in this browser. An account saves it properly, syncs it across devices, and lets you edit the cards.
1.What does a convex lens do?
It converges parallel rays of light to a point called the principal focus.
2.What does a concave lens do?
It causes parallel rays of light to diverge, spreading them out.
3.What is the principal focus of a convex lens?
The point where rays parallel to the axis are brought together after passing through the lens.
4.What is the focal length?
The distance from the centre of the lens to the principal focus.
5.What is a real image?
One formed where light rays actually meet, which can be projected onto a screen.
6.What is a virtual image?
One that appears to come from where rays only seem to originate. It cannot be projected onto a screen.
7.What type of image does a concave lens always produce?
A virtual image, which is upright and smaller than the object.
8.When does a convex lens produce a virtual image?
When the object is closer to the lens than the focal length. The image is then upright and magnified.
9.When does a convex lens produce a real image?
When the object is further from the lens than the focal length. The image is then inverted.
10.State the equation for magnification.
magnification = image height divided by object height
11.Does magnification have a unit?
No. It is a ratio of two lengths, so the units cancel.
12.An object 2 cm tall gives an image 6 cm tall. Calculate the magnification.
6 divided by 2 = 3.
13.What does a magnification less than 1 mean?
The image is smaller than the object.
14.How is a convex lens drawn in a ray diagram?
As a vertical line with outward arrowheads at each end.
15.Give an application of a convex lens.
A magnifying glass, and the lens in a camera or the human eye.
16.Why do objects appear coloured?
They absorb some wavelengths of visible light and reflect or transmit others, and the reflected ones reach your eye.
17.Why does a red object look red?
It reflects red light and absorbs the other colours.
18.What colour does a white object appear in red light?
Red, because a white object reflects all colours and only red is available.
19.What does a colour filter do?
It transmits only certain wavelengths and absorbs the rest.
20.What is the difference between transparent, translucent and opaque?
Transparent transmits light clearly, translucent transmits it but scatters it, and opaque transmits none at all.
21.What is a perfect black body?
An object that absorbs all the radiation that hits it, reflecting and transmitting none.
22.What is special about a perfect black body as an emitter?
It is also the best possible emitter of radiation.
23.Do all objects emit radiation?
Yes. All bodies emit and absorb infrared radiation, whatever their temperature.
24.What happens as the temperature of an object rises?
It emits more radiation overall, and the peak of the emitted radiation moves to shorter wavelengths.
25.What determines the temperature of an object?
The balance between the rate at which it absorbs radiation and the rate at which it emits it.
26.How does this apply to the Earth?
The Earth absorbs radiation from the Sun and emits infrared. If absorption exceeds emission the temperature rises, which is what greenhouse gases affect.
You remember far more by trying to recall an answer than by reading it. Run these as flashcards and the ones you keep getting wrong will come back more often.
Start studyingOr see the other Waves decks.