11th Physics Assignment-1 Answer Key
Unit :- 1 Nature Of Physical World And Measurement
11th Physics Assignment-1 Answer Key:- This is TN Samacheerkalvi / Tamil Nadu State Board / TNSCERT 11th Standard Physics English Medium Unit -1 . Nature of Physical World and Measurement Questions and Answer Key
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11th Physics – Assignment-1 Answer Key
Unit :- 1 Nature Of Physical World And Measurement
Part – A
I. Choose the best answer.
1.One of the combinations from the fundamental physical constants is. The unit of this expression is
a) kg2 b) m3 c) s-1 d) m
Answer :- a) kg2
2.If the error in the measurement of radius is 2% then the error in the determination of volume of the square will be
a) 8% b) 2% c) 4% d) 6%
Answer :- d) 6%
3.If the length and time period of an oscillating pendulum have error of 1% and 3% respectively then the error in measurement of acceleration due to gravity is
a) 4% b) 5% c) 6% d)7%
Answer :- d)7%
4.The length of the body is measured as 3.51m if the accuracy is 0.01m, then the percentage error in the measurement is
a) 351% b) 1% c) 0.28% d) 0.035%
Answer :- c) 0.28%
5.Which of the following has the highest number of significant figures?
a) 0.007m2 b) 2.64x 1024kg c) 0.0006032 m2 d ) 6.3200 J
Answer :- d) 6.3200 J
6. If 3.14, then the value of is
a) 9.8596 b) 9.860 c) 9.86 d) 9.9
Answer :- c) 9.86
7.Which of the following pairs of physical quantities have same dimension?
a) force and power b) torque and energy c) torque and power d) force and torque
Answer :- c) torque and power
8.The dimensional formula of Planck’s constant h is
a) [ML2T-1] b) [ML2T-3] c) [MLT-1] d) [ ML3T-3]
Answer :- a) [ML2T-1]
9.The velocity of a particle V at an instant t is given by v=at+. The dimension of b is
a) [L] b) [LT-1] c) [LT -2] d) [LT-3]
Answer :- d) [LT-3]
10.The dimensional formula for gravitational constant G is
a) [ ML3T-2] b) [ M-1L3T-2] c) [M-1L-3 T-2 ] d) [ ML-3 T2]
Answer :- b) [ M-1L3 T-2]
Part – B
II. Very short answer
1.Define the unit of length
1 Meter is the unit of length, one meter is the length of the path travelled by light in vacuum in 1/299,792,458 of a second
2.Define mole
One mole is the amount of substance that contains as many elementary entities as there are atoms in 0.012kg of pure carbon -12.
3.Define kilogram
One kilogram is the mass of the prototype cylinder of platinum-iridium alloy (whose height is equal to its diameter), preserved at the International Bureau of weights and measures at Services, Near Paris, France
4.Define second
One second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of Caesium -133 atom
5.Define Kelvin
Kelvin is defined as temperature of the triple point of the water
Part – C
III. Short answer
1.How will you measure the diameter of the moon using the parallax method?
Parallax is the name given to the apparent change in the position of an object with respect to the background when the object is seen from two different positions
- Let O be the angle subtended by Moon at the surface of the Earth
- d is the distance of the moon from earth
- D is the diameter of the Moon
- From this, the diameter of the Moon, D=d.θ
- By knowing the value of d and θ,the diameter of the Moon can be calculated
2.Write the rules for determining significant figures
Answer:- All non-zero digits are significant
Eg. 1234 has four significant figures
All zeros between two non-zero digits are significant
Eg: 2008 has four significant figures
All zeros to the right of a non-zero digit, but to the left of a decimal point are significant
Eg: 30700 has five significant figures.
If the number is less than 1, the zero(s) on the right of the decimal point but to the left of the first non-zero digit are not significant
Eg,40.00 has four significant figures
The number of significant figures does not depend on the system of units used
Eg :1.53 cm, 0.0000153km all have three significant figures
Part – D
IV. Long answer.
1.Explain the use of a Screw gauge and Vernier caliper in measuring smaller distances. (1.5.1 – Screw gauge and Vernier caliper)
Measurement of small distance
Screw Gauge:
The screw gauge is an instrument used for measuring the dimensions of objects accurately up to a maximum of 50mm. The principle of the instrument is the magnification of linear motion using the circular motion of a screw. The least count of the screw gauge is 0.01mm.
Vernier Caliper:
A vernier caliper is a versatile instrument for measuring the dimension of an object namely the diameter of a hole, or the depth of a hole, The least count of the vernier caliper is 0.01cm.