UNITS AND MEASUREMENTS QUIZ - 12
Dear Readers,
JEE Advanced paper is considered to be one of the toughest entrance exams in India. Moreover, this Physics is considered the toughest subject because it is the most application-based. The student needs to get the basics right and then move on to mastering advanced concepts. Units and Measurements consist of nearly about 3-4 % of marks in the Physics section.
Q1. Statement 1: Force cannot be added to pressure
Statement 2: Because their dimensions are different
Statement 2: Because their dimensions are different
Solution
(a)
Addition and subtraction can be done between quantities having same dimensions
(a)
Addition and subtraction can be done between quantities having same dimensions
Q2. Statement 1: Parallax method cannot be used for measuring distances of stars more than 100 light years away
Statement 2: Because parallax angle reduces so much that it cannot be measured accurately
Solution
(a)
As the distance of star increases, the parallax angle decreases, and great degree of accuracy is required for its measurement. Keeping in view the practical limitation in measuring the parallax angle, the maximum distance a star we can measure is limited to 100 light year
(a)
As the distance of star increases, the parallax angle decreases, and great degree of accuracy is required for its measurement. Keeping in view the practical limitation in measuring the parallax angle, the maximum distance a star we can measure is limited to 100 light year
Q3. Statement 1: Mass, length, and time are fundamental quantities
Statement 2: Mass, length, and time are independent of one another
Statement 2: Mass, length, and time are independent of one another
Solution
(a)
Fundamental quantity is that quantity which does not depend upon other quantities. Since mass, length and time are independent of one another, so they are fundamental quantities
(a)
Fundamental quantity is that quantity which does not depend upon other quantities. Since mass, length and time are independent of one another, so they are fundamental quantities
Q4. Statement 1: Out of three measurements, l=0.7 m; l=0.70 m and l=0.700 m, the last one is most accurate
Statement 2: In every measurement, only the last significant digit is not accurately known
Solution
(b)
The last number is most accurate because it has greatest significant figure (3)
(b)
The last number is most accurate because it has greatest significant figure (3)
Q5. Statement 1: The size of the nucleus of an atom is not very small
Statement 2: One Fermi is equal to 10-12 m.
Statement 2: One Fermi is equal to 10-12 m.
Solution
(d)
The radius of the nucleus of an atom is of the order of 1 fermi. 1 fermi = 10-15 m(small unit)
(d)
The radius of the nucleus of an atom is of the order of 1 fermi. 1 fermi = 10-15 m(small unit)
Q6. Statement 1: Surface tension and surface energy have the same dimensions
Statement 2: Because both have the same S.I unit
Statement 2: Because both have the same S.I unit
Solution
(c)
As surface tension and surface energy both have different S.I. unit and same dimensional formula
(c)
As surface tension and surface energy both have different S.I. unit and same dimensional formula
Q7. Statement 1: Now a days a standard metre is defined in terms of the wavelength of light
Statement 2: Light has no relation with length
Statement 2: Light has no relation with length
Solution
(c)
Because representation of standard metre in terms of wavelength of light is most accurate
(c)
Because representation of standard metre in terms of wavelength of light is most accurate
Q8. Statement 1: The light year and wavelength consist of dimensions of length.
Statement 2: Both light year and wavelength represent distances.
Statement 2: Both light year and wavelength represent distances.
Solution
(a)
Light year is distance travelled by light in vacuum in 1 year.
1 light year = 9.45 × 1015 m
The wavelength is the distance between two consecutive crests or through of a wave.
The dimension of both light year and wavelength is [M˚LT˚]. So, both represent distances.
(a)
Light year is distance travelled by light in vacuum in 1 year.
1 light year = 9.45 × 1015 m
The wavelength is the distance between two consecutive crests or through of a wave.
The dimension of both light year and wavelength is [M˚LT˚]. So, both represent distances.
Q9. Statement 1: The number of significant figures in 0.001 is 1, while in 0.100 it is 3
Statement 2: Zeros before a non-zero significant digit are not counted while zeros after a non-zero significant digit are counted
Statement 2: Zeros before a non-zero significant digit are not counted while zeros after a non-zero significant digit are counted
Solution
(a) Zeros before a non-zero significant digit are not counted, while zeros after a non-zero significant digit are counted
(a) Zeros before a non-zero significant digit are not counted, while zeros after a non-zero significant digit are counted
Q10. Statement 1: The time period of a pendulum is given by the formula, T=2Ï€√(g/l)
Statement 2: According to the principle of homogeneity of dimensions, only that formula is correct in which the dimensions of L.H.S. is equal to dimensions of R.H.S
Statement 2: According to the principle of homogeneity of dimensions, only that formula is correct in which the dimensions of L.H.S. is equal to dimensions of R.H.S
Solution
