Measurements and Experimentation Exe-1A System of Unit Numericals for ICSE Class-9 Concise Selina Publishers. There is the solutions of Numericals Questions of your latest textbook which is applicable in 2023-24 academic session. Visit official Website CISCE for detail information about ICSE Board Class-9.
Measurements and Experimentation Exe-1 A System of Unit Numericals Questions Solutions
ICSE Physics for Class-9 Concise Selina Publishers
| Board | ICSE |
| Class | 9 |
| Subject | Physics |
| Writer / Publication | Concise selina Publishers |
| Chapter-1 | Measurements and Experimentation |
| Exe – 1 A | System of Unit |
| Topics | Solution of Exe-1(A) Numericals |
| Academic Session | 2023-2024 |
System of Unit numericals problems / questions for practice, conversion of one unit into other unit in very simple and easy way. Therefore practice these important questions/ problems to learn conversion of unit in effective way.
Exe-1A System of Unit Numericals
Measurements and Experimentation in Physics for ICSE Class-9 of Concise Selina Publishers Chapter-1
Page 11
Question 1. The wavelength of light of a particular colour is 5800 Å. Express it in (a) nanometre and (b) metre.
Answer : Wavelength of light of particular colour = 5800 Å
(a) 1 A = 10-1 nm
5800 A = 58
00 × 10-1 nm
= 580 nm
(b) 1 A = 10-10 m
5800 A= 5800 × 10-10 m
= 5.8 × 10-7 m
Question 2. The size of bacteria is 1 µ. Find the number of bacteria present in 1 m length.
Answer : Size of a bacteria = 1 µ , Since 1 µ = 10-6 m
Number of the particle = Total length/size of one bacteria
= 1 m/10-6 m = 106
Question 3. The distance of a galaxy is 5·6 × 1025 m. Assuming the speed of light to be 3 × 108 m s “. Find the time taken by light to travel this distance .
[Hint : Time taken = distance/speed ]
Answer : Distance of galaxy = 5.6 × 1025 m and Speed of light = 3 × 108 m/s
(a) Time taken by light = Distance travelled/speed of light
= (5.6 × 1025 / 3 × 108) s
= 1.87 × 1017 s
Question 4. The wave length of light is 589 nm. What its wavelength in Å ?
Answer : 1 nm= 10 Å Therefore 589 nm = 10×589A°= 5890 Å
Question 5. The distance of the nearest star, Proxima Centauri, from the Earth is 4.0 x 1013 km. Express it in light year.
Answer : 1 Light year = 9.46 x 1012 km
or 9.46 x 1012 km = 1 Light year
∴ 4.0 x 1013 km
= 1/(9.46×1012 x 4.0 x 1013
= 4.2 light years.
Question 6. It takes time 8 min for light to reach form the sun to the earth surface . If speed of light is taken to be 3 × 108 m/s, find the distance from the sun to the earth in km.
Answer : 1 Min= 60 sec So 8 Min= 8×60 = 480 sec
Now distance = Speed×Time
= 3×108×480
=1.44×108 Km/s
Question 7. ‘The distance of a star form the earth is 8.33 light minutes .’ What do you mean by this statements ? Express the distance in meter.
Answer : It means light take 8.33 Minute to reach the star while the speed of light is 3×108 m/s.
Distance= Speed × Time
= 3×108 × 8.33×60
=1.5×1011Mitre
— : End of Me
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