物理光的反射和折射 DSE、CE 選擇題

1.

Photograph of a bird and its clear image on a calm water surface

A clear image of a bird is formed by a calm water surface as shown in the above figure. Which of the following statements about the image is/are correct ?

(1)The image is real.

(2)A clear image is formed as regular reflection occurs.

(3)If the bird is closer to the water surface, the size of the image increases.

2.

When a light ray travels from air to glass, which of the following descriptions about the changes of the speed, the frequency and the wavelength of the ray is correct ?

Speed	Frequency	Wavelength
remains unchanged	increases	decreases
remains unchanged	decreases	increases
decreases	remains unchanged	decreases
increases	remains unchanged	increases

3.

Telecommunication companies nowadays use optical fibres to transmit data. What are the advantages of using optical fibres over copper wires in transmitting data ?

(1)Less data loss in the transmission.

(2)Data can be transmitted at a higher rate.

(3)For the same data transmission rate, optical fibres take up less space.

4.

A ray of light enters a transparent rectangular block from air and emerges. Which of the following ray diagrams is/are impossible ? The dotted lines represent normal to the surfaces.

Three ray diagrams (1), (2), (3) of a ray entering and leaving a rectangular block, with angles 40, 45 and 50 degrees marked

5.

A student performs an experiment to find the refractive index of a material and the result is shown below. Which of the following set of data is likely to be wrong ?

	$P$	$Q$	$R$	$S$
Angle of incidence	$20^\circ$	$40^\circ$	$60^\circ$	$80^\circ$
Angle of refraction	$14^\circ$	$22^\circ$	$38^\circ$	$44^\circ$

6.

A ray of light enters a transparent rectangular block and travels along the path as shown in the figure above. Find angle $\theta$ .

Ray entering a rectangular block at angle theta to the left face and leaving along the top at 40 degrees

7.

Two coloured lights X and Y travelling from vacuum into glass along the same path in glass

Two coloured lights, $X$ and $Y$ , travel from vacuum to glass. They undergo refraction and travel along the same path in glass. Which of the following descriptions about the two coloured lights is correct ?

8.

Three 45-90-45 triangular prisms X, Y and Z with a ray entering normally; the emergent rays differ

$X$ , $Y$ and $Z$ are three $45^\circ$ $-$ $90^\circ$ $-$ $45^\circ$ triangular prisms made of different transparent materials. A ray incident normally at one face is found to undergo refraction and reflection in each prism as shown in the figures above. Which of the following is the correct order of the refractive indices of the prisms ?

9.

Plane mirror MN on a wall, observer E 1 m from the wall and 1.5 m above ground, and a 3 m post PQ 4 m behind the observer

In the figure, a plane mirror $MN$ of height $h$ is mounted in an adjustable vertical position on a vertical wall. $E$ is an observer's eye which is $1$ m from the wall and $1.5$ m above the ground. $PQ$ is a vertical post of height $3$ m and is $4$ m behind the observer. Looking into the mirror the observer can see the whole image of the post. What is the minimum value of $h$ ?

10.

A light ray undergoes reflection and refraction at an air-glass boundary as shown. $PQ$ is perpendicular to $RS$ . $OX$ , $OY$ and $OZ$ are the paths of the light rays. Which of the following deductions is/are correct ?

(1)

OX

is the path of the incident ray.

(2)

RS

is the air-glass boundary.

(3)The light ray travels from glass to air.

Rays OX, OY and OZ at the point O on line RS, with PQ perpendicular to RS; angles 60, 40 and 60 degrees marked