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Waves · Part 2 of 2
18 exam-style questions with model answers, plus 24 quick multi-choice questions — every question on this part of the standard, grouped by the 6 pages of notes they come from.
Write a full answer before you reveal the model one. That comparison is where the learning happens.
Light travels from air into a glass block of refractive index with an angle of incidence of .
Calculate the angle of refraction.
Light passes from water () into air with an angle of incidence of .
Calculate the angle of refraction, and explain why the ray bends away from the normal in this case.
A narrow beam of light in air strikes one face of a rectangular glass block () at an angle of incidence of , passes through the block, and emerges from the opposite, parallel face.
Calculate the angle of refraction inside the block and the angle at which the light emerges. Explain fully why the emerging beam is parallel to the original beam, and describe what else has changed about the light while it was inside the glass.
A material has a refractive index of .
Calculate the critical angle for a boundary between this material and air.
A ray of light inside a water tank () strikes the water–air surface at an angle of incidence of .
Calculate the critical angle for water and air, and explain what happens to the ray.
An optical fibre has a glass core of refractive index .
Calculate the critical angle at the core–air boundary. Explain fully how the fibre keeps light travelling along its length, and explain why total internal reflection is used rather than coating the inside of the fibre with a mirror. Comment on what would happen if the fibre were bent very sharply.
A ray of light travelling parallel to the principal axis strikes a converging lens.
State the path of the ray after it passes through the lens.
An object is placed between and in front of a converging lens.
Describe the image formed, giving its nature, orientation and size, and explain how a ray diagram shows the image is real.
A student uses a converging lens of focal length cm as a magnifying glass. Starting with the lens very close to a small object, they slowly move the lens away. At first the object appears enlarged and upright, but at a certain point the image suddenly blurs and then reappears upside down.
Explain fully what is happening at each stage, and identify the object distance at which the change occurs.
An object is placed cm from a converging lens of focal length cm.
Calculate the image distance.
An object cm tall is placed cm from a converging lens of focal length cm.
Calculate the image distance and the height of the image, and describe the image fully.
A converging lens has a focal length of cm. An object is placed first at cm from the lens, then moved to cm from the lens.
Calculate the image distance and magnification in each case. Explain fully what the change in the sign of the image distance means physically, and explain why the two situations correspond to a projector and a magnifying glass respectively.
State the three properties of the image formed by a diverging lens, for any object position.
An object is placed cm from a diverging lens of focal length cm.
Calculate the image distance, and explain why a diverging lens can never form a real image.
A converging lens of focal length cm and a diverging lens of focal length cm are each used with an object placed cm away.
Calculate the image distance and magnification in each case, and compare the two images. Explain fully why the diverging lens behaves the same way for every object distance while the converging lens does not.
State the nature of the image formed by a convex mirror, and give one everyday use of this type of mirror.
An object is placed cm in front of a concave mirror of focal length cm.
Calculate the image distance, and describe the image formed. Explain what the sign of your answer tells you.
A car's passenger-side wing mirror is convex with a focal length of m. A car m tall is m behind it. The mirror carries the warning "objects in mirror are closer than they appear".
Calculate the image distance and the image height. Explain fully why a convex mirror is used despite this drawback, and explain why the warning is necessary.