MCQs 9th Physics Ch1 New Book
MCQs 9th Physics Ch1 New Book will be solved with complete detail.
Multiple Choice Questions (MCQs) 9th Physics chapter 1 New Book
Tick the correct answer.
1.1 The instrument that is most suitable for measuring the thickness of a few sheets of cardboard is
(a) meter rule (b) Measuring tape (c) Vernier Callipers (d) micermeter screw gauge
Option C is correct.
Reason:- Vernier callipers precisely measures the thickness of cardboard sheets due to its flat jaw.
1.2 One femtometer is equal to
$$(a)\;10^{-9}m\;(b)\;10^{-15}m\;(c)\;10^9m\;(d)\;10^{15}m$$
Option B is correct.
Reason:- Femto means 10 to raised power -15. In Nuclear physics, we use this unit.
1.3 A light year is a unit of
(a) light (b) time (c) distance (d) speed
Option C is correct.
Reason:- Light year is a distance that light travels in 1 year in vacuum. In Astronomy, we use this unit.
$$Speed\;of\;light\;is\\3\;\times\;10^8\;m\;s^{-1}\;$$
1.4 Which one is a non-physical quantity ?
(a) distance (b) density (c) colour (d) temperature
Option C is correct.
Reason:-Colour depends on observer.
1.5 When using a measuring cylinder, one precaution to take is to:
(a) check for the zero error (b) look at the meniscus from below the level of the water surface (c) take several readings by looking from more than one direction (d) position the eye in line with bottom of the meniscus
Option D is correct.
Reason:- Correct position of eye will almost eliminate the chances of human error.
1.6 Volume of water consumed by you per day is estimated in:
(a) millilitre (b) litre (c) kilogram (d) cubic meter
Option B is correct.
Reason:- Litre its a convenient unit for everyday life.
1.7 A displacement can is used to measure:
(a) mass of a liquid (b) mass of a solid (c) volume of a liquid (d) volume of a solid
Option D is correct.
Reason:- Displacement can can measure volume of regular as well as irregular shaped solid by displacement method.
We can directly measure mass of liquid and solid with the help of balance and measuring cylinder can measure the volume of a liquid.
1.8 Two rods with lengths 12.321 cm and10.3 cm are placed side by side, the difference of their lengths is:
(a) 2.02 cm (b) 2.0 cm (c) 2 cm (d) 2.021 cm
Option B is correct.
Reason:- There are 5 significant figures in 12.321 and 3 significant figures in 10.3. So we will use only 3 first significant figures in 12.321. Hence, 12.3 – 10.3 = 2.0
We can also say that 12.321 is accurate to 3 decimal places and 10.3 is accurate to 1 decimal place. So, final answer must be round of to 1 decimal place. Hence 12.321-10.3 = 2.021 is raw subtraction and when we round of 2.021 up to 1 decimal place, we will get 2.0
1.9 Four students measure the diameter of a cylinder with vernier callipers. which of the following reading is correct ?
(a) 3.4 cm (b) 3.475 cm (c) 3.47 cm (d) 3.5 cm
Option C is correct.
Reason:- Least count of vernier calliper is 0.01 cm which is 2 decimal places and there are also 2 digits after the decimal in 3.47.
1.10 Which of the following measures are likely to present the thickness of a sheet of this book ?
$$(a)\;\;6\times10^{-25}\;m\;\;\;(b)\;1\times10^{-4}\;m\\\\(c)\;1.2\times10^{-15}\;m\;\;(d)\;4\times10^{-2}\;m$$
Option B is correct.
Reason:- Measurements in option a and c are very small and measurement in option d is 4 cm. Option B is 0.1 mm so, its correct.
1.11 In a vernier callipers ten smallest divisions of the vernier scale are equal to nine smallest divisions of the main scale. If smallest division of the main scale is half millimetre, the vernier constant is equal to:
(a) 0.5 mm (b) 0.1 mm (c) 0.05 mm (d) 0.001 mm
Option C is correct.
Reason:- 10 vernier scale division is equal to 9 main scale division.
Least count or vernier constant = 1 main scale division – 1 vernier scale division
= 1 mm – 0.9 mm = 0.1 mm
Its given that 10 VSD = 9 MSD and 1MSD = Half millimetre
So, 10 VSD = 9 ( o.5 mm ) = 4.5 mm
Hence 1VSD = 4.5/10 = 0.45 mm
vernier constant = 1 main scale division – 1 vernier scale division
VC = 0.5 mm – 0.45 mm = 0.05 mm
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