First 3 Chapter Test

Download Tamil Nadu 9th Standard Science question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.

Questions:

Multiple Choice Question

10 x 1 = 10

Virtual and magnified image is formed by________________________mirror

(a)

concave

(b)

convex

(c)

plane

(d)

both concave and convex

Light year is the distance travelled by light in ________.

(a)

one year

(b)

two years

(c)

10 years

(d)

5 years

Area under a velocity time graph gives ______

(a)

time taken by an object

(b)

distance travelled by an object

(c)

acceleration

(d)

retardation

The slope of the velocity time graph for uniformly accelerated motion give _____

(a)

speed

(b)

acceleration

(c)

displacement

(d)

velocity

During uniform motion, the change in velocity is _______

(a)

zero

(b)

infinity

(c)

constant

(d)

one

____________is the fundamental quantity.

(a)

Length

(b)

Area

(c)

Volume

(d)

Density

When the reflecting surface is curved outwards the mirror formed will be

(a)

concave mirror

(b)

convex mirror

(c)

plane mirror

(d)

spherical mirror

The force responsible for drying of clothes in a washing machine is

(a)

Centripetal force

(b)

Centrifugal force

(c)

Gravitational force

(d)

Electrostatic force

Slope of the velocity - time graph gives

(a)

speed

(b)

displacement

(c)

distance

(d)

acceleration

10.

Which among the following is not a device to measure mass?

(a)

Spring balance

(b)

Beam balance

(c)

Physical balance

(d)

Digital balance

Generic 2

5 x 2 = 10

11.

A student takes 15 minutes to travel from his home to school with a uniform speed of 5km/h. What is the distance of his school from the home?

12.

What do you conclude about the speed of light in diamond if you are told that the refractive index of diamond is 2.41?

13.

Name the spherical mirror(s) that has/have
i) Virtual principal focus
ii) Real principal focus

14.

Give two examples of transparent medium that are denser than air

15.

What is the full form of SI system?

Generic 4

5 x 4 = 20

16.

The diagram shows the position of a ball it rolls down a track - the ball took 0.5s sec to roll from one position to other.
(a) State where the motion of the ball is uniform or non-uniform motion.
(b) What is the distance travelled by the ball in 2.5 s?
(c) Find the average velocity of the ball from. A to F.

17.

What are the fundamental physical quantities and their units?

18.

The speed of a particle is constant. Will it have acceleration? Justify with an example.

19.

A bus travel, a distance of 20 km from Chennai central airport in 45 minutes. What is the average speed?

20.

Write the rules that are followed in writing the symbols of units in SI system.

Read the passage and answer the questions

1 x 1 = 1

21.

Read the passage and answer the question given below.
Mass is the amount of matter contained in an object. Measurement of mass helps us to distinguish between a lighter and a heavier body. Beam balance, spring balance and electronic balance are used to measure mass of different objects. The SI unit of mass is the kilogram (kg). But different units are used to measure the mass of different objects. E.g. weight (mass) of a tablet is measured in milligrams (mg), weight of a student is measured in kilogram (kg) and weight of a truck with goods is measured in metric tons. 1 metric ton is equal to 10 quintals and 1 quintal is equal to 100 kg. 1 gram is equal to 1000 mg.
How will you measure the weight of a tablet?
a. kg b. g
c. mg d. None of these

Problems

2 x 2 = 4

22.

An Athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 m and 20 s?

23.

Inian and Ezhilan argue about the light year. Inian tells that it is 9.46 × 10¹⁵ m and Ezhilan argues that it is 9.46 × 10¹² km. Who is right? Justify your answer.

Fill in the blanks

5 x 1 = 5

24.

Light has maximum speed in______________

25.

When a ray of light travels from______________________ to rarer it bends away from the normal

26.

Give an example of a motion in which the displacement is zero, but the distance travelled is not zero ______

27.

The mirror used in search light is ________ .

28.

Negative acceleration is called ____________

Generic 7

1 x 7 = 7

29.

State and verify laws of refraction using a glass slab.

Assertion and reason

2 x 2 = 4

30.

Mark the correct choice as:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.
Assertion: When an object moves with constant speed along a circular path, the motion is called uniform motion.
Reason: When an object is moving with a constant speed along a circular path, the velocity changes due to the change in direction.

31.

Mark the correct choice as:
(a) Both assertion and reason are true and reason in the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.
Assertion: The accelerated motion of an object may be due to change in magnitude of velocity or direction or both of them.
Reason: Acceleration can be produced only by change in magnitude of the velocity it does not depend the direction.

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Answers Key:

Multiple Choice Question

10 x 1 = 10

(a)
concave

(a)
one year

(b)
distance travelled by an object

(b)
acceleration

(a)
zero

(a)
Length

(a)
concave mirror

(b)
Centrifugal force

(d)
acceleration

10.

(a)
Spring balance

Generic 2

5 x 2 = 10

11.

Speed = 5 km/m = \(\frac { 5000 }{ 3600 } \) m/s
Time = 15 min = 15 x 60 sec
Distance = Speed x time
=\(\frac { 5000 }{ 3600 } \) x 15 x 60 = 1250 m

12.

Refractive index \(\mu \) of diamond = The refractive index is linked to the relative speed of propagation of light in different media. Light propagates with different speeds in different media. (i.e.,) light travels faster in vacuum than in medium.
When light travels from air to diamond the refractive index of the diamond with respect to air.
\(The\ refractive\ index\ \mu =\frac { Speed\ of\ light\ in\ air }{ Speed\ of\ light\ in\ medium } \\ 2.42=\frac { Speed\ of\ light\ in\ air }{ Speed\ of\ light\ in\ diamond } \)
This means the speed of light in air is 2.41 times the speed of light in diamond. The speed of light in diamond is lesser than speed of light in air.

13.

(i) Convex and (ii) Concave

14.

Water, glass.

15.

Full form of SI system is "International system of units"

Generic 4

5 x 4 = 20

16.

(a) It is a non-uniform motion
(b) 20 cm
(c) Velocity = \(\frac { Displacement }{ time\ taken } \)
=\(\frac { Total\ distance }{ time\ taken } \)
=\(\frac { 20\times 10^{ -2 } }{ 2.5 } \)
= \(\frac { 2 }{ 2.5 } \) = 0.08 m/s (or) cm/s.

17.

Fundamental quantities	Unit	Symbol
Length	metre	m
Mass	kilogram	kg
Time	second	s
Temperature	kelvin	K
Electric current	ampere	A
Luminous intensity	candela	cd
Amount of substance	mole	mol

18.

The acceleration will be zero. When the speed of a particle is constant, its acceleration which is rate of change of velocity will also be zero since change in velocity will be zero.

19.

Average speed =\(\frac { Total\ distance }{ time\ taken } \)
Total distance = 20 km = (2 x 1000) m
Time taken = 45 min = (45 x 60) s
Average speed = \(\frac { 2\times 1000 }{ 45\times 60 } =\frac { 200 }{ 27 } \)= 7.4 m/s

20.

1. The units named after scientists are not written with a capital intial letter.
Ex: newton, henry, ampere and watt
2. The symbols of units named after scientists should be written by the initial capital letter.
Ex: N for newton, H for henry, A for ampere and W for watt.
3. Small letters are used as symbols for units not derived from a proper noun.
Ex: m for metre, kg for kilogram
4. No full stop or other punctuation marks should be used within or at the end of the symbols.
Ex: 50 m and not as 50 m.
5. The symbols of the units are not expressed in plural form.
Ex: 10 kg not as 10 kgs.
6. Accepted symbols should only be used.
Ex: ampere should not be written as amp and second should not be written as sec.

Read the passage and answer the questions

1 x 1 = 1

21.

Problems

2 x 2 = 4

22.

Track diameter \((\mathrm{d})=200 \mathrm{~m} ; \quad \mathrm{r}=\frac{200}{2}=100 \mathrm{~m}\)
Time taken for one rotation = 40 s
Total distance of the track \(=2 \pi r\)
\(=2 \times 3.14 \times 100 \)
\(=2 \times 314 \)
\(=628 \mathrm{~m}.\)
Displacement at the end of 2 m and 20 s =(2 x 60) + 20
=140 second
40 second =1 rotation
140 second \(=\frac{140}{40}=3.5\) rotation.
distance covered = 628 x 3.5
= 2198 m
displacement = 200 m

23.

Inian's statement is correct
Because light travels 3 x 10⁸ m in one second total number of second in one
year is equal to 365 x 24 x 60 x 60 = 3.153 x 10⁷ second.
So one light year is = (3.153 x 10⁷) x (3 x 10⁸)
= 9.46 x 10¹⁵ m

Fill in the blanks

5 x 1 = 5

24.

()
Vacuum

25.

()
denser

26.

()
Circular motion

27.

()
concave mirror

28.

()
retardation (or) deceleration

Generic 7

1 x 7 = 7

29.

The laws of refraction of light : The incident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence, all lie in the same plane. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a light of given colour and for the given pair of media. This law is also known as Snell's law of refraction.
If i is the angle of incidence and r is the angle of refraction, then
\(\frac { \sin { i } }{ \sin { r } } =constant\)
Verification of laws of refraction :

(1) Fix a sheet of white paper on a drawing board using drawing pins.
(2) Place a rectangular glass slab over the sheet in the middle. Draw the outline of the slab with a pencil. Let us name the outline as ABCD. Take four identical pins.
(3) Fix two pins. Say E and F, vertically such that the line joining the pins is inclined to the edge AB.
(4) Look for the images of the pins E and F through the opposite edge. Fix two other pins, say G and H, such that these pins and the images of E and F lie on a straight line.
(5) Remove the pins and the slab.
(6) Join the prints of the pins E and F and let it meet AB at O. Let EF meet AB at O. Similarly, join the prints of the pins G and H and Let it meet HG at O'. Join o and O'. Also produce EF as shown by a dotted line in Figure.
(7) Draw a perpendicular NN' to AB at O and another perpendicular MM' to CD at O'. In this activity, you will note that, the light ray has changed its direction at points O and O'. Note that both the points O and O' lie on surfaces separating two transparent media. The light ray has entered from air to glass and has bent towards the normal that is from a rarer to denser medium.
(8) The light ray has emerged from glass to air that is from a denser medium to a rarer medium. The light here has bent away from the normal. Compare the angle of incidence with the angle of refraction at both refracting surfaces AB and CD.
(9) In Figure, EO is the incident ray OO' the refracted ray and O'H the emergent ray. You may observe that the emergent ray is parallel to the direction of the incident ray.
(10) The extent of bending of the ray of light at the opposite parallel faces AB (air-glass interface) and CD (glass-air-interface) of the rectangular glass slab is equal and opposite. This is why the ray emerges parallel to the incident ray.