1) Calculate the depth of sea when waves are sent with velocity 1490 m/sec and time of reflection is 0.1 sec.

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2) A person stands between two mountains then he made a sound he heard two echoes. The first after 1.4 seconds and the second after 1 second from the first echo. Calculate the distance between him and each mountain taken that speed of sound in air 340 m/sec.

Because they produce ultrasonic waves determine places of things in front of them.  

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Because they have concave surfaces that collect sound and concentrate it.

N ature of light waves work sheet five

Question One: Complete the following:

1- Light is considered as ………. waves. Their wave length ranges between ………. : ………. Nanometer.

2- ………. is the distance travelled by light in one second.

3- The white light consists of ………. colours started with ………. and ended by ………. .

4- Energy of light quantum = ……… × frequency.

5- Increasing the thickness of medium decreasing the ……… of light through it.

6- The light propagates in air as ………lines.

7- Light intensity is the amount of light that falls ……… on the unit area in one second.

8- Light intensity ……… proportional with square of distance between surface and ………

9- Air is ……… medium, while milk is ………

10- We can use ……… to analyze light.

Question Two: Give Reasons for:

1- The energy of red light is smaller than orange colour.

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2- We can’t see impurities in black honey. ………………………………………………………………………………………………………………………………

3- Energy of light quantum depends on its frequency.

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4- Light intensity is inversely proportional with square of distance. ………………………………………………………………………………………………………………………………

Question Three:Write the scientific term:

1- Electromagnetic waves travel in straight lines. ……………………………….

2- Dispersing white light into seven colours. ……………………………….

3- Instruments used to analyze white light. ……………………………….

4- The colour of lowest frequency. ……………………………….

5- The scientist who proved that light consists of quantum of light. ……………………………….

6- A medium that doesn’t allow light to pass through…………………………

7- The amount of light that falls perpendicular on the unit area in one second. ……………………………….

8- The light intensity is inversely proportional with square of distance between surface and source of light. ……………………………….

W ork sheet six Reflection and refraction of light

Question One: Complete the following:

1- The rebounding of light rays back to the source is called ……… of light.

2- The reflection of light can be divided into ……… or ……… .

3- When the light falls on rough surface it is called ……… reflection.

4- Angle of incidence = ……… .

5- If the light ray falls ……… it reflects on itself where angle of ……… =……… equal zero.

6- The ……… instrument is used in submarines.

7- The light ……… are used in medical ……… to make operations without surgery.

8- The ability of medium to refract light is called ……… .

Question Two: Give reasons for:

1- Occurrence of Mirage. ………………………………………………………………………………………………………………………………..

2- The perpendicular light ray reflects on itself. ………………………………………………………………………………………………………………………………..

3- Objects are seen some times upnormal. ……………………………………………………………………………………………………………………………

4- The bottom of swimming pool is seen higher than its real place.

… ……………………………………………………………………………………………………………………………..5- The refractive index is greater than (1).

………………….…………………………………………………………………………………………………………..6- Occurrence of light refraction.

………………………………………………………………………………………………………………………………..Question Three: Write the scientific term:

1- The rebounding of light waves on falling on a reflecting surface.

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2- The reflection of light rays in one direction on falling on smooth surface. …………………………..

3- The reflection of light rays in different directions from rough surface. …………………………..

4- Angle of incidence = angle of reflection. ……………………………..

5- Instrument used in submarines to see under water………………………

6- The angle between refractive ray and perpendicular line………………

7- The change of light direction on transferring from transparent medium to another. …… …………………

8- The relation between light velocity in air and light velocity in medium. ……………………………

9- The angle when the incident angle in the medium of lowest density = 90ْ …………………………….

Q uestion Four: What is meant by?

1- Refractive index of water is 1.3

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2- Seeing objects upside dwon in desert at noon time.

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3- Light reflects on itself.

……………………………………………………………………………………………………………………………. Question Five:Problems:

Calculate the refractive index of diamond if the light velocity in it is 1.25 × 108 m/sec

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  Work sheet seven    Reproduction in flowering plants

Q uestion One: Complete the following:

1- The flower grows on ……… bud on the ……… .

2- The male organ in flower is ……… while the female organ is ………

3- The male flower has ……… whorls which are ………, ……… and ……… .

4- The stamen consists of ……… ended by ……… .

5- The pistil in flower consists of ………, style and ……… .

6- The anther consists of ……… sacs contain ……… .

7- Pollination is done by transferring ……… from ……… to ……… .

8- Pollination in large coloured flowers is done by ……… .

 9- The flower that has four whorls is called ……… and its sex is …

10- As an example for unisexual flower is ……… .

11- The flower is the ……… organ in plant.

12- The pollination in the same flower is ……… .

13- If the ovary contains many ovums it forms ……… seeds as in ……… plant.

14- A sexual reproduction in plants is divided into ……… and ………

Question Two: Write the scientific term:

1- The reproductive system in flowering plants. ………………………………….

2- The complete flower. ………………………………….

3 - Male reproductive organs in flower. …….………………………

4- Female reproductive organs in flower. ………………………………….

5- Transfer of pollen grains from anther to stigma. ……………………………

6- Green colored leaves surround the flower. ………………………………….

7- Swollen part hold the flower parts. ………………………………….

8- Reproduction by green parts in flower. ………………………………….

9- Male cells spread in air. ………………………………….

10- The cell formed from combination of male cell with female cell. ……………………………….

11- The flower that contains pistil and stamen. ………………………………….

Question Three: Give reasons for:

1- Palm trees are unisexual flower. ………………………………………………………………………………………………………………………………

2- Sun plant is not having self pollination. ……………………………………………………………………………………………………………………………… 3- Stigma of flowers is sticky. To stick with pollen grains.  ……………………………………………………………………………………………………………………………… 4- Flowers have coloured petals. ………………………………………………………………………………………………………………………………

5- Onion flower is typical bisexual flower. ………………………………………………………………………………………………………………………………

6- Bees have important for plants. ……………………………………………………………………………………………………………………………… i

7 - Some flowers are hanged in air anthers..

……………………………………………………………………………………………………………………………… 8- Olive plant contains one seed. ………………………………………………………………………………………………………………………………

9- Man makes pollination in some plants. ………………………………………………………………………………………………………………………………

To produce important crops as date in palm

Question Four: Study the following figure then answer: