Year 11 general questions 2

Which of the following conditions is necessary for a ray of light travelling from grass to water to be totally internally reflected? The

• Angle of incidence in glass most be less than the critical angle.

• Incident ray must lie along the boundary of the two media.

• Angle of incidence in glass must be greater than the critical angle.

• Angle of incidence in glass must be equal to the critical angle.

The refractive index of a medium relative to air is 1.8. Calculator, to the nearest degree, the critical angle for the medium.

• 60°

• 56°

• 34°

• 18°

Totally reflecting prisms are preferred to mirrors in periscopes because

• Mirrors give multiple images.

• Silvering on mirrors is easily damaged.

• Mirrors reflect less light that totally reflecting prism.

• All of the above.

A person can focus an object only when it is within 200cm from him. Which spectacles should be used to increase his maximum distance of distinct vision to infinity?

• Plane glasses

• Concave lens

• Convex lens

• Binoculars

A magnified and virtual image of a near object is produced by

• Prism binocular.

• Astronomical telescope.

• Periscope.

• Simple microscope.

A converging lens produces an image 4 times as large as an object placed 25cm from the lens. Calculate its focal length.

• 100cm

• 33cm

• 29cm

• 20cm

A converging lens has a focal length of 5cm. Determine its power.

• +20.0D

• +0.2D

• -20.0D

• 0.2D

Which of the following correctly describes the image formed by a diverging lens?

• Diminished, erect and virtual.

• Diminished, inverted and real.

• Magnified, erect and virtual.

• Magnified, inverted and real.

The inability of the eye to focus near objects is known as

• Astigmatism

• Eye ring

• Hypermetropia

• Myopia

• Presbyopia

A converging lens of focal length 15cm forms a virtual image at a point 10cm from the lens. Calculate the distance of the object from the lens.

• 10cm

• 5cm

• 6cm

• 1.5cm