Light: question bank

Q1

FoundationLuminous sources and straight lines

Which of these is luminous — it makes its own light?

The MoonA fireflyA mirrorA book page

Q2

FoundationLuminous sources and straight lines

Why can you not see anything in a completely dark, sealed room?

Your eyes stop working in the darkThere is no light to enter your eye from any objectDark rooms absorb your eyesightObjects change colour to black in the dark

Q3

FoundationLuminous sources and straight lines

A beam of light passing through a dusty room looks like a straight line. What does this show?

Light only travels through dustLight travels in a straight lineDust makes its own lightLight bends around dust particles

Q4

FoundationLuminous sources and straight lines

Sort: which of these is non-luminous?

The SunA lit candleVenus, the evening starA lightning flash

Q5

CoreLuminous sources and straight lines

A pinhole camera shows an image of a candle flame that is upside down. Why?

The pinhole flips images on purposeLight from the top of the flame travels in a straight line down through the pinhole to the bottom of the screen, and vice versaThe candle flame is actually upside downLight bends as it passes through the tiny hole

Q6

CoreLuminous sources and straight lines

A pinhole camera box is 20 cm long. A tree 12 m tall stands 8 m from the pinhole. Using image height = object height × (box length ÷ object distance), how tall is the image, in centimetres?

Your answer (cm)

Q7

CoreLuminous sources and straight lines

A material lets you see a blurry, unclear shape of what is behind it, but not sharp detail. What is it?

TransparentTranslucentOpaqueLuminous

Q8

StretchLuminous sources and straight lines

A torch is switched on inside a sealed, perfectly black box with no gaps. From outside, in a dark room, you see nothing. What is the best explanation?

The torch instantly stopped workingLight travels in straight lines and none can escape the box, since it is opaque and sealedLight needs an audience to existBlack boxes absorb electricity, not light

Q9

FoundationShadows, umbra, penumbra and sundials

A shadow forms because:

Light bends around an opaque objectAn opaque object blocks light travelling in straight linesThe object absorbs all nearby lightShadows are a trick of the eye, not real light

Q10

FoundationShadows, umbra, penumbra and sundials

The umbra of a shadow is:

The grey, partly lit fringe of a shadowThe fully dark centre of a shadow, where no part of the source is visibleAnother name for the object itselfOnly found during eclipses

Q11

CoreShadows, umbra, penumbra and sundials

A 10 cm tall toy is placed 40 cm from a small torch bulb. A wall stands 160 cm from the same bulb. Using shadow = object × (lamp-to-screen ÷ lamp-to-object), how wide is the shadow, in centimetres?

Your answer (cm)

Q12

CoreShadows, umbra, penumbra and sundials

Using shadow = object × D ÷ d: a 30 cm puppet is held 60 cm from a lamp, with a screen 300 cm from the same lamp. How tall is the shadow, in centimetres?

Your answer (cm)

Q13

CoreShadows, umbra, penumbra and sundials

Why does a bird flying 50 m above the ground cast no visible shadow, even in bright sunshine?

Birds are too light to block sunlightThe Sun's own angular width blurs the shadow's umbra completely away at that height, leaving only a faint, invisible penumbraBirds move too fast for a shadow to formSunlight cannot reach 50 m above the ground

Q14

StretchShadows, umbra, penumbra and sundials

On a Zero Shadow Day in Bengaluru, a vertical pole at local noon:

Casts its longest shadow of the yearCasts no shadow at all, because the Sun is exactly overheadCasts a shadow pointing north instead of southThis never happens in India

Q15

StretchShadows, umbra, penumbra and sundials

Using shadow length = height ÷ tan(Sun's altitude), what is the shadow of a 1 m stick when the Sun is 60° above the horizon? Give your answer to 2 decimal places.

Your answer (m)

All 80 questions