3rd prep science

8/9/2019 3rd Prep Science

1/16


2/16

(2)

Science3rd preparatoryMidterm First term

19) Physical quantity can be identical by knowing magnitude and

direction.20) Physical quantity like (mass – time – distance).

21) Physical quantity like (velocity – displacement – acceleration).

22) Physical quantities which is characterized by magnitude only.

23) The displacement in an interval of time of one second.

24) A vector quantity that equals velocity over time.

(2) Give reasons for:

1) The velocity is a vector quantity.

2) The magnitude of acceleration can be given from the (velocity – time)

graph.

3) Displacement is a vector quantity while distance is a scalar quantity.

4) Velocity is a vector quantity.

5) When the body moves with a uniform velocity, it has no

acceleration.

6) When the body moves with an acceleration, the graphical relation

(displacement – time) is not a straight line.

(3) Compare between:

1) Velocity and Acceleration

2) Uniform acceleration and Non-uniform acceleration

3) Uniform velocity and Non-uniform velocity

(4) Define:

1) Velocity 2) Uniform velocity

3) Non uniform velocity 4) Acceleration

5) Uniform acceleration 6) Non-uniform acceleration


3/16

(3)


(5) What is meant by:

1) The displacement of a body is 50 m?

2) A car moves by a velocity of 60 m/s?

3) A car moves by average velocity of 80 km/h?

4) A train moves by an uniform acceleration 5 m/s2?

(6) Problems

1) A car moves at initial speed 15 m/s. It reaches a speed of 20 m/s in

2.5 sec. Calculate the acceleration.

2) A jumbo jet (Boeing 747) lands. It touches the ground at a speed of

160 m/s and takes 32 s to come to rest find the acceleration of this jet.

3) A train is moving at a speed of 20 m/s. When the brakes are

applied, it deceleration at 2 m/s2 find the time needed for the train to

stop.

(7) Mention what does the following graphs represents:

d

t

Fig. (1)

d

t

Fig. (2)

d

t

Fig. (3)

v

t

Fig. (4)

v

t

Fig. (5)


4/16

(4)


(8) Choose the correct answer:

1) A vector quantity is completely defined by:

a) knowing its direction only.

b) knowing its magnitude only

c) knowing both its magnitude and direction

2) A scalar quantity is completely defined by:

a) knowing its magnitude only.

b) knowing its direction onlyc) knowing both its magnitude and direction

3) Velocity is the:

a) ratio of the change in velocity to the time for this change.

b) ratio of the change in displacement to the time for this change.

c) product of displacement and time for the change.

4) Acceleration:

a) ratio of the change in velocity to the time for this change.

b) ratio of the change in displacement to the time for this change.

c) product of velocity and time.

(9)

1) the graphical relation (displacement – time)

2) The graphical relation (velocity – time)


5/16


6/16

(6)


2) Choose the right answer:

1) If the radius of curvature of spherical mirror = 40 cm, its focal length

= ………… (15 cm – 20 cm – 40 cm – 80 cm)

2) The incident light ray that passes through the center of a concave

mirror reflects passing through.

(focus – pole of the mirror – center of curvature of mirror)

3) An imaginary point in the center of the lens lies on the principal axis

is ………… (real focus – secondary focus – optical center – center of curvature)

4) The lens is a transparent medium that ………… light.

(refracts light – reflects – does not pass light)

5) If a body at a distance = 10 cm from a plane mirror, the distance

between the image and the body is …………

(20 cm – 10 cm – 5 cm – 100 cm)

6) If the angle between the incident light ray and the reflected ray 30

then the angle of reflection = ………… (60 - 15 - 30 - 90)

7) When a light ray falls perpendicular on a transparent medium, then it

……… (reflects – refracts – reflects on itself – passes without deviation)

8) The incident ray that passes through the focus reflects …………

(passing through the center of curvature – parallel to the principal

axis – perpendicular to the principal axis – reflects on itself)

(3) Correct the underline words:

1) The radius of curvature equals to half of the focal length.

2) From the properties of the formed image by plane mirror is(inverted)

3) The (focal length) of the convex mirror is the distance between the

center of curvature of the mirror and any point of the mirror surface.


7/16

(7)


4) The light ray that falls perpendicular on the reflecting surface

reflects with an angle that equals (9)5) The radius of curvature of the spherical mirror equals (its focal length)

(4) Give reason for:

1- the perpendicular incident ray on a reflecting surface reflects on

itself.

2- Concave mirror is called convergent mirror.

3- Convex mirror is called divergent mirror.

4- Convex lens is known as a convergent lens.

5- Concave lens is known as a divergent lens.

(5) What happen when…?

1- When a light ray falls perpendicular on a reflecting surface ( a plane

mirror) to the surface of reflecting at the point of incidence.

2- The incident ray is parallel to the principal axis of the concave mirror.

3- The incident ray that passes through the focus of a concave mirror.

4- The incident ray that passes through the curvature center of a

concave mirror.

5- The incident ray that is parallel to the principal axis of a convex

mirror.6- The incident ray its extension passes through the focus of a convex

mirror.

7- The incident ray that its extension passes through the curvature

center of a convex mirror.

8- The ray that falls parallel to the principal axis of a convex lens.

9- The ray that falls passing through the focus of a convex lens.


8/16

(8)


10- The ray that falls passing through the optical central of the lens

(the vision center of the lens) of a convex lens or concave lens.11- The ray that falls parallel to the principal axis of a concave lens.

(6) Compare between:

1- Concave mirror and convex mirror

2- Real focus and virtual focus of the mirror

3- Convex lens and concave lens

4- Principal focus and secondary focus of a spherical mirror.

5- Principal focus and secondary focus on convex lens.


9/16

(9)


Unit (2) Light energy

(1) Give scientific term:

1- Angle of incidence = Angle of reflection. (……………...)

2- The light ray that falls on reflecting surface. (……………...)

3- The change of direction of light ray in the same medians.

(……………...)

4- A mirror which gives virtual, erect and equal in size image for an

object. (……………...)

5- A straight line connecting the center of curvature of the mirror and

any point on its surface besides the poles of the mirrors.

(……………...)

6- The distance between the pole of the mirror and its focus.

(……………...)

7- The image formed by the convex mirror or by the concave lens can't

be received on the screen. (……………...)

8- A transparent medium refracts the light. (……………...)

9- The lens is thick at the center and less thickness at the tip.

(……………...)

10- The point inside the lens on the principal axis in the mid distance

between its faces.

11- The image which is formed due to the collection of the refractedrays and can be received on a screen. (……………...)

12- The vision defect in which the person can see the near objects

only clearly. (……………...)

13- The lens that corrects the short-sight. (……………...)

14- A kind of lenses that is used instead of glasses and can stick to the

eye cornea. (……………...)


10/16

(10)


(2) Complete:

1- The phenomenon of the light bouncing off in the same medium

when it meets the reflecting surface is called ……………...

2- When a light ray falls perpendicular on a reflecting surface, its angle

of reflection equals ……………...

3- Mirrors are …………... surfaces for light, they may be ……………...

or ……………...

4- Convex mirror ……………... the light rays and its reflecting surfaceand it ……………... light rays after reflection.

5- The point that is in the middle of the reflecting surface the spherical

mirror is called ……………...

6- ……………... is any straight line that passes by the center of

curvature of the mirror and any point on its surface except pole.

7- Focal length =

8- The radius of the concave mirrors equals ………... of its focal length.

9- …………... image can be received on a screen, while ……………...

image can't.

10- If an object put at ……………... of the concave mirror, a real

……………... image and equal to the object is formed.

11- To obtain a magnified erect image for your face, you should stand

in front of a concave mirror at distance.

12- A convex mirror has a focal vertex of 20 cm. Then half the

diameter of its spherical surface equals ……………...

13- The optical center is the ……………... point on the principal axis

through which the incident ray passes without ……………...

14- The focal length of the convex lens equals the distance between

……………... and ……………...


11/16

(11)


15- When an object is placed between the focus and the center of

cvature, the formed image is real ……………... and ……………... 16- The normal person can see clearly the near objects at distance

less than …………..., and for objects at a distance up to …………...

17- …………... and …………... are the most important of vision defects.

18- The reasons of short eye sightedness is ………... and …………...

19- The short sighted person needs a medical eye glasses with

……………... lenses. 20- The vision defect which is due to shortness in the radius of the eye

sphere is called ……………...

21-

45º

60º

CF

F CF

CF


12/16

(12)


22- A long-sighted person needs a medical eye glasses with ………...

lens.23- The contact lenses are ver y …………... lenses made of …………..

and can stick to the eye ……………... by the eye fluid.

(3) Give reason for:

1- The perpendicular incident light ray on a plane mirror reflects on

itself.

2- The word AMBULANC is written in a converted way on the ambulance.

3- The spoon made of silver is a spherical mirror.

4- Concave mirror is used for solar ovens.

5- The convex mirror is called diverging mirror.

6- The focal length of a spherical mirror can be determined by knowing

its radius.

7- The focal vertex of the thick convex lens is less than the thin convex

lens.

8- The collective lens has two foci, but the collective mirror has one focus.

9- The object that is placed at the focus of a convex lens has not an

image.

10- Some persons have short-sight.

11- Concave lens is used to treat short-sighted person.

12- The retina is close to the eye in the long-sighted person.

13- The long-sightedness is treated by using a convex lens.


13/16

(13)


(4) Problems:

1) If the measure of the angle between the incident ray x and reflect

ray is 140, find the angle of incidence and the angle of reflection?

What is the relation between them?

2) A person stands infront of a plane mirror at a distance of 10 meters.

What is the distance he must move so that the distance between

him and his image becomes 6 meters?

3) Find the focal length of a concave mirror that its diameter is 20 cm.4) Explain only by drawing the formation of the image that is equal to

the object by means of a convex lens.

5) A convex lens with a focal length of 10 cm an object was placed at a

distance of 20 cm from the lens. Assign the distance of the object's

image from the lens and mention its properties.


14/16

(14)


Model AnswersUnit (2)(1) Give the scientific term:

1- 1st law of light reflection 2- reflecting light ray

3- reflection of light 4- plane mirror

5- secondary axis of mirror 6- focal length7- virtual image 8- the lens

9- convex lens 10- optical center

11- real image 12- short sight

13- concave lens 14- contact lenses

(2) Complete:

1- light reflection 2- zero

3- reflecting, plane and spherical 4- divergent

5- pole of the mirror 6- secondary axis of mirror

7-

8- twice

9- real , virtual 10- center , inverted

11- Less than focal length 12- 40 cm

13- mid - refraction

14- primary focus , optical center

15- magnified and inverted 16- 25 cm , 6 meters

17- short sight , long sight

18- the increase in the eye ball diameter , increase the convexity


15/16


16/16

(16)


6- Because the radius = 2 × focal length.

7- Because radius of this lens is bigger than that of the thick lens.8- Because convex lens has two circular surfaces, but the

concave mirror has one circular surface.

9- Because the penetrating ray from a lens doesn't meet and pass

through a parallel way.

10- Due to:

- The increase in the eye ball diometes.- The increase in convexity of the eye lens surface.

11- Because convex lens collects rays before the eye to forming it

on the rectira

12- Due to the decrease of the eye ball diameter.

13- Because the convex has collects the rays, so the image of the

object is formed on the retina

(4) Problems:

1) = 70º

Incidence angle = reflect angle

2) 7 meter

3) diameter = 4 focal length

Focal length =

= 5 cm

4)

5) The distance = 20 cmIts properties: real – inverted – equal to object

F

C

FC

3rd prep science

Documents