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All questions of Physics and Measurement for JEE Exam
Can you explain the answer of this question below:The error in two readings of A are 0.01 and -0.03, then mean absolute error is ?- A:0.002
- B:-0.004
- C:0.02
- D:-0.02
The answer is c.
The error in two readings of A are 0.01 and -0.03, then mean absolute error is ?
A:
0.002
B:
-0.004
C:
0.02
D:
-0.02
|
Bhargavi Bajaj answered |
Mean absolute error = (|0.01|+|-0.03|)/2
= 0.02
= 0.02
Can you explain the answer of this question below:The method used to measure the distance of a planet from the earth is- A:Parallax method
- B:Archimedes’ method
- C:Newton’s method
- D:Galileo’s method
The answer is a.
The method used to measure the distance of a planet from the earth is
A:
Parallax method
B:
Archimedes’ method
C:
Newton’s method
D:
Galileo’s method
|
Yash Ghoshal answered |
The astronomers mainly use parallax method to find distances to objects like other planets. To calculate the distance to a star or to a planet, astronomers observe it from different places along Earth's orbit around the Sun.
Which of the following physical quantity has different dimension than others?
- a)Energy
- b)Watt hour
- c)Momentum
- d)Work
Correct answer is option 'C'. Can you explain this answer?
Which of the following physical quantity has different dimension than others?
a)
Energy
b)
Watt hour
c)
Momentum
d)
Work
|
Riya Banerjee answered |
Dimension of work and energy are the same i.e. [ML²T⁻²].
Power = Energy/Time,
Energy = Power × Time (in terms of hour instead of second),
Energy = Watt × Hour,
= [ML²T⁻³] [T],
= [ML²T⁻²].
But, Momentum(p) = Mass × Velocity,
p = [M] [LT⁻¹],
p = [MLT⁻¹].
Hence the Dimension of work, energy and watt-hour is the same i.e. [ML²T⁻²] but the dimension of momentum is different ([MLT⁻¹]).
Power = Energy/Time,
Energy = Power × Time (in terms of hour instead of second),
Energy = Watt × Hour,
= [ML²T⁻³] [T],
= [ML²T⁻²].
But, Momentum(p) = Mass × Velocity,
p = [M] [LT⁻¹],
p = [MLT⁻¹].
Hence the Dimension of work, energy and watt-hour is the same i.e. [ML²T⁻²] but the dimension of momentum is different ([MLT⁻¹]).
The number of significant digits in 8.1000 is- a)3
- b)1
- c)5
- d)4
Correct answer is option 'C'. Can you explain this answer?
The number of significant digits in 8.1000 is
a)
3
b)
1
c)
5
d)
4
|
Krishna Iyer answered |
There are three rules on determining how many significant figures are in a number:
- Non-zero digits are always significant.
- Any zeros between two significant digits are significant.
- A final zero or trailing zeros in the decimal portion ONLY are significant.
Keeping these rules in mind, we can say that there are 5 significant digits.
Can you explain the answer of this question below:Identify the pair whose dimensions are equal. [AIEEE 2002]- A:Torque and work
- B:Stress and energy
- C:Force and stress
- D:Force and work
The answer is a.
Identify the pair whose dimensions are equal. [AIEEE 2002]
A:
Torque and work
B:
Stress and energy
C:
Force and stress
D:
Force and work
|
|
Shreya Gupta answered |
The dimensions of torque and work are [ML^2T^−2] because both of these are the product of force and distance.
Which is the most accurate atomic clock?- a)Carbon-12 clock
- b)Carbon atom clock
- c)caesium atom clock
- d)Stop clock
Correct answer is option 'C'. Can you explain this answer?
Which is the most accurate atomic clock?
a)
Carbon-12 clock
b)
Carbon atom clock
c)
caesium atom clock
d)
Stop clock
|
Nandini Patel answered |
According to the most accurate caesium atomic clock in the world, 1 second is the time that elapses during 9,192,631,770 cycles of the radiation produced by the transition between two levels of the caesium 133 atom.
The most suitable instrument for measuring the size of an atom is.- a)Electron microscope
- b)Vernier calliper
- c)Optical Microscope
- d)Screw gauge
Correct answer is 'A'. Can you explain this answer?
The most suitable instrument for measuring the size of an atom is.
a)
Electron microscope
b)
Vernier calliper
c)
Optical Microscope
d)
Screw gauge
|
Mira Sharma answered |
Only electron microscope has resolution of 0.5-0.6 Angstrom which is less than the size of an atom.
Three physical quantity having dimensions [ M L-1 T-2] are.- a)Stress, pressure, density
- b)Stress, pressure, work
- c)Stress, pressure, coefficient of elasticity
- d)Stress, pressure, torque
Correct answer is option 'C'. Can you explain this answer?
Three physical quantity having dimensions [ M L-1 T-2] are.
a)
Stress, pressure, density
b)
Stress, pressure, work
c)
Stress, pressure, coefficient of elasticity
d)
Stress, pressure, torque
|
Trisha Vashisht answered |
Pressure = Force/Area = ML1T-2/ L2 = [M L-1 T-2]
Stress = Force/Area = ML1T-2/ L2 = [ML-1T-2]
Coefficient of elasticity = Stress/Strain = [ML-1T-2]
Stress = Force/Area = ML1T-2/ L2 = [ML-1T-2]
Coefficient of elasticity = Stress/Strain = [ML-1T-2]
Hence, the correct answer is C.
Can you explain the answer of this question below: Which of the following is caused by careless handling?
- A:
Systematic error
- B:
Gross error
- C:
Random error
- D:
None of the mentioned
The answer is b.
Which of the following is caused by careless handling?
Systematic error
Gross error
Random error
None of the mentioned
|
|
Nandini Iyer answered |
Gross errors are mostly due to lack of knowledge, judgment and care on the part of experiment. That is Gross error is caused by careless handling.
The SI unit of length is the meter. Suppose we adopt a new unit of length which equals to x meters. The area 1m2 expressed in terms of the new unit has a magnitude-- a)x
- b)x2
- c)
- d)
Correct answer is option 'D'. Can you explain this answer?
The SI unit of length is the meter. Suppose we adopt a new unit of length which equals to x meters. The area 1m2 expressed in terms of the new unit has a magnitude-
a)
x
b)
x2
c)
d)
|
|
Trisha Vashisht answered |
We have 1 unit = x meters
So 1 unit2 = x2 meter2
Hence, we get 1 meter2 = 1/x2 unit2
So 1 unit2 = x2 meter2
Hence, we get 1 meter2 = 1/x2 unit2
The number of significant digits in 48,923 is- a)2
- b)4
- c)3
- d)5
Correct answer is option 'D'. Can you explain this answer?
The number of significant digits in 48,923 is
a)
2
b)
4
c)
3
d)
5
|
Rohit Joshi answered |
There are three rules on determining how many significant figures are in a number: Non-zero digits are always significant.Any zeros between two significant digits are significant.A final zero or trailing zeros in the decimal portion ONLY are significant.Keeping these rules in mind, we can say that there are 5 significant digits.
The number of significant digits in 0.007 is- a)4
- b)3
- c)2
- d)1
Correct answer is option 'D'. Can you explain this answer?
The number of significant digits in 0.007 is
a)
4
b)
3
c)
2
d)
1
|
Om Desai answered |
There are three rules on determining how many significant figures are in a number:
- Non-zero digits are always significant.
- Any zeros between two significant digits are significant.
- A final zero or trailing zeros in the decimal portion ONLY are significant.
So, keeping these rules in mind, there are 1 significant digit.
The velocity (in cm s-1) of a particle is given in terms of time t (in s) by the equation 
The dimensions of a, b and c are- a)L T 2, L T, L
- b)L T -2, L, T
- c)L2, T, L T -2
- d)L, L T, T 2
Correct answer is 'B'. Can you explain this answer?
The velocity (in cm s-1) of a particle is given in terms of time t (in s) by the equation
The dimensions of a, b and c area)
L T 2, L T, L
b)
L T -2, L, T
c)
L2, T, L T -2
d)
L, L T, T 2
|
|
Raghav Bansal answered |
Volume of water = Volume of the tank = Length * breadth * height = 5.6 * 8.2 * 12.8 = 587.776
Volume, correct up to 4 significant figure = 587.8
The error in two readings of A are 0.01 and -0.03, then mean absolute error is ?- a)0.002
- b)-0.004
- c)0.02
- d)-0.02
Correct answer is 'C'. Can you explain this answer?
The error in two readings of A are 0.01 and -0.03, then mean absolute error is ?
a)
0.002
b)
-0.004
c)
0.02
d)
-0.02
|
Anagha Sharma answered |
Mean absolute error = (|0.01|+|-0.03|)/2
= 0.02
= 0.02
A dimensionless quantity- a)has no unit
- b)must have a unit
- c)cannot exist
- d)might have a unit
Correct answer is option 'D'. Can you explain this answer?
A dimensionless quantity
a)
has no unit
b)
must have a unit
c)
cannot exist
d)
might have a unit
|
|
Rajeev Saxena answered |
A unit need not always mean a physical unit. So a dimensionless quantity will always be independent of the base units — meter, second, kilograms, kelvin, candela, moles, ampere.
But there are other quantities that are dimensionless, but have a unit. For example, radian is the unit for an angle. But it is dimensionless because it is defined to be the ratio of two lengths.
The numbers of significant figures in 1.84 x10-27 kg are:- a)five
- b)thirty
- c)three
- d)four
Correct answer is option 'C'. Can you explain this answer?
The numbers of significant figures in 1.84 x10-27 kg are:
a)
five
b)
thirty
c)
three
d)
four
|
|
Suresh Iyer answered |
As the given number is itself written in the format of powers of ten, it is very obvious that all the non significant zeros are considered by the power of the and hence all the rest digits that are 3 in number are significant.
Which of the following is caused by careless handling?- a)Systematic error
- b)Gross error
- c)Random error
- d)None of the mentioned
Correct answer is option 'B'. Can you explain this answer?
Which of the following is caused by careless handling?
a)
Systematic error
b)
Gross error
c)
Random error
d)
None of the mentioned
|
|
Mira Sharma answered |
Gross errors are caused by experimenter carelessness or equipment failure.
This category basically takes into account human oversight and other mistakes while reading, recording and the readings. The most common of errors, the human error in the measurement fall under this category of errors in measurement. For example the person taking the reading from the meter of the instrument he may read 23 as 28. Gross errors can be avoided by using two suitable measures and they are written below:
1. proper care should be taken in reading, recording the data. Also, calculation of error should be done accurately.
2. By increasing the number of experimenters we can reduce the gross errors. If each experimenter takes different reading at different points, then by taking average of more readings we can reduce the gross errors
Dimensions cannot be used to- a)check dimensional correctness of a formula
- b)convert units
- c)find value of the constant of proportionality in an equation
- d)deduce a relation among physical quantities
Correct answer is option 'C'. Can you explain this answer?
Dimensions cannot be used to
a)
check dimensional correctness of a formula
b)
convert units
c)
find value of the constant of proportionality in an equation
d)
deduce a relation among physical quantities
|
Preeti Iyer answered |
- Dimensional Equations are used to derive the Relations between the Physical quantities . Also, they are used to check the correctness of the Equation by the Principle of the homogeneity of the dimensions. Hence, Option (a) and option (b) are true for the Dimensional equation. Thus, It is not correct for the given questions.
- Dimensional Equations are not valid for the Pure numbers since they are non-dimensional constants.and also they do not provide the Value of the Constant of the Proportionality.
- Thus, we can also say that all equations which are correct must be dimensionally correct but all those equations which are dimensionally correct may or may not be accurately correct. Thus, Option Option (c). is correct answer for the Given question.
- Dimensional Equations are used for the conversions of the units thus this option can not be correct for the given question.
Find the option with 3 significant figures.- a)0.0268
- b)2.068
- c)2.608
- d)26.08
Correct answer is option 'A'. Can you explain this answer?
Find the option with 3 significant figures.
a)
0.0268
b)
2.068
c)
2.608
d)
26.08
|
|
Raghav Bansal answered |
0.0268 have three significant figures where as 2.608 cm, 26.08 mm and 2.068 cm have four significant figures.
Light year is the unit of- a)Speed
- b)Mass
- c)Distance
- d)Time
Correct answer is option 'C'. Can you explain this answer?
Light year is the unit of
a)
Speed
b)
Mass
c)
Distance
d)
Time
|
Pooja Shah answered |
The light-year is a unit of length used to express astronomical distances and measures about 9.46 trillion kilometres or 5.88 trillion miles. As defined by the International Astronomical Union, a light-year is the distance that light travels in vacuum in one Julian year.
The significant digits in 0.000532 are:
- a)2, 3
- b)5, 3, 2
- c)0,5,3,2
- d)5, 3
Correct answer is option 'B'. Can you explain this answer?
The significant digits in 0.000532 are:
a)
2, 3
b)
5, 3, 2
c)
0,5,3,2
d)
5, 3
|
Rishu Singh answered |
Option B is correct
5, 3 and 2 are significant figures in 0.000532
zero before furst non zero digit from left are always
INSIGNIFICANT
5, 3 and 2 are significant figures in 0.000532
zero before furst non zero digit from left are always
INSIGNIFICANT
The product of energy and time is called action. The dimensional formula for action is same as that for- a) Power
- b) Angular energy
- c)Force × velocity
- d) Impulse × distance
Correct answer is option 'D'. Can you explain this answer?
The product of energy and time is called action. The dimensional formula for action is same as that for
a)
Power
b)
Angular energy
c)
Force × velocity
d)
Impulse × distance
|
Hansa Sharma answered |
Both are different from each other.
Energy × Time=(M1L2T−2)×(T1)=M1L2T−1
Force × Velocity=(M1L1T−2)×(L1T−1)=M1L2T−3
Impulse × distance=(M1L1T−1)×(L1)=M1L2T−1
Power=M1L2T−3
Angular Energy=M1L1T−2
Energy × Time=(M1L2T−2)×(T1)=M1L2T−1
Force × Velocity=(M1L1T−2)×(L1T−1)=M1L2T−3
Impulse × distance=(M1L1T−1)×(L1)=M1L2T−1
Power=M1L2T−3
Angular Energy=M1L1T−2
where symbols have their usual meaning, are [AIEEE 2003]Numbers of significant figures in the volume of a cube of side 6.103 m are:- a)2
- b)4
- c)3
- d)1
Correct answer is option 'B'. Can you explain this answer?
Numbers of significant figures in the volume of a cube of side 6.103 m are:
a)
2
b)
4
c)
3
d)
1
|
|
Raghav Bansal answered |
- As per rule, zero between two non zero digits are significant.
- The number of a significant figure in the length of the side is 4.
- So the calculated volume should be rounded off to 4 significant figures. Multiplying numbers do not increase significant figures.
If a and b are two physical quantities having different dimensions then which of the following can denote a new physical quantity- a)a + b
- b)a – b
- c)a/b
- d)ea/b
Correct answer is option 'C'. Can you explain this answer?
If a and b are two physical quantities having different dimensions then which of the following can denote a new physical quantity
a)
a + b
b)
a – b
c)
a/b
d)
ea/b
|
|
Suresh Reddy answered |
Quantities with different dimensions cant be added or subtracted. Also the dimension of the product of the quantities in power is always one. But when two quantities are multiplied the dimension of the product is the product of the dimensions of the initial quantities.
Error in the measurement of radius of a sphere is 1%. The error in the calculated value of its volume is- a)1%
- b)3%
- c)5%
- d)7%
Correct answer is option 'B'. Can you explain this answer?
Error in the measurement of radius of a sphere is 1%. The error in the calculated value of its volume is
a)
1%
b)
3%
c)
5%
d)
7%
|
|
Raghav Bansal answered |
∵ V = (4/3)πr3
% error is volume = 3 × error in radius = 3 × 1 = 3%
% error is volume = 3 × error in radius = 3 × 1 = 3%
Which of the following is not the unit of energy?- a)watt-hour
- b)electron-volt
- c)N × m
- d)kg × m/sec2
Correct answer is option 'D'. Can you explain this answer?
Which of the following is not the unit of energy?
a)
watt-hour
b)
electron-volt
c)
N × m
d)
kg × m/sec2
|
Rajat Patel answered |
Newton • meter = F.d --> work
foot-pound (symbol: ft.lb) is a unit of work or energy (Wiki)
watt for power
kilowatt hour, or kilowatt-hour, (symbol kWh, kW h or kWh) is a unit of energy (Wiki)
joule for energy.
Population of a town is reported as 157,900 . Which of the following statements correct?- a)the population is 157900
20 - b)the population is 157900 50
- c)the population is 157900100
- d)the population is 15790025
Correct answer is 'B'. Can you explain this answer?
Population of a town is reported as 157,900 . Which of the following statements correct?
a)
the population is 157900 20
20b)
the population is 157900 50
50c)
the population is 157900100
100d)
the population is 15790025
25
|
Arun Khanna answered |
Here, 157900 (the significant digits are underlined here) implies that the population is believed to be within the range of about 157850 to about 157950. In other words, the population is 157900�50. The “plus-or-minus 50” appended to this number means that we consider the absolute uncertainty of the population measurement to be 50 – (–50) = 100. We can also say that the relative uncertainty is 100/157900, which we can also express as 1 part in 1579, or 1/1579 = 0.000633, or about 0.06 percent.
Can you explain the answer of this question below:The physical quantities not having same dimensions are [AIEEE 2003]
- A:
Torque and work
- B:
Momentum and Planck's constant
- C:
Stress and Young's modulus
- D:
Speed and 
The answer is b.
The physical quantities not having same dimensions are [AIEEE 2003]
Torque and work
Momentum and Planck's constant
Stress and Young's modulus
Speed and
|
|
Mira Sharma answered |
Torque has same dimension as work, Stress has same dimensions as Young's modulus,Speed and (μ0∈0)^(−1/2) have same dimensionsbut Momentum and Plank's constant do not have same dimensionsHence b is the correct answer.
PARSEC is a unit of- a)Time
- b)Angle
- c)Distance
- d)Velocity
Correct answer is option 'C'. Can you explain this answer?
PARSEC is a unit of
a)
Time
b)
Angle
c)
Distance
d)
Velocity
|
|
Raghav Bansal answered |
The parsec (symbol: pc) is a unit of length used to measure large distances to astronomical objects outside the Solar System. A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond, which corresponds to 648000π astronomical units.
Can you explain the answer of this question below:The numbers of significant figures in 9.1 x10-31 kg are:
- A:
three
- B:
two
- C:
ten
- D:
twenty one
The answer is b.
The numbers of significant figures in 9.1 x10-31 kg are:
three
two
ten
twenty one
|
|
Om Desai answered |
As the power of 10 is irrelevant to the determination of significant figures hence, the numbers of significant figures are 2 (9 and 1).
Find the option with 5 significant figures- a)26.08mm
- b)0.02608m
- c)2.608cm
- d)2.6008 cm
Correct answer is option 'D'. Can you explain this answer?
Find the option with 5 significant figures
a)
26.08mm
b)
0.02608m
c)
2.608cm
d)
2.6008 cm
|
|
Preeti Iyer answered |
In option a, b and c, we only have 4 significant figures in the number
In option d, the number has 5 significant figures.
The number of significant digits in 2,076 is- a)3
- b)5
- c)2
- d)4
Correct answer is option 'D'. Can you explain this answer?
The number of significant digits in 2,076 is
a)
3
b)
5
c)
2
d)
4
|
|
Preeti Iyer answered |
There are three rules for determining how many significant figures are in a number:
- Non-zero digits are always significant.
- Any zeros between two significant digits are significant.
- A final zero or trailing zeros in the decimal portion ONLY are significant.
Keeping these rules in mind, we can say that there are 4 significant digits.
Angstrom is the unit of- a)time
- b)mass
- c)light
- d)length
Correct answer is option 'D'. Can you explain this answer?
Angstrom is the unit of
a)
time
b)
mass
c)
light
d)
length
|
Vishal Giri answered |
Ya ri8 angstrom this unit used to measure length. 1 A = 10^ - 10 m
Can you explain the answer of this question below:A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance?
- A:
450
- B:
600
- C:
500
- D:
550
The answer is c.
A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance?
450
600
500
550
|
|
Preeti Iyer answered |
► Time can be converted as t = (8 x 60) + 20s = 500 seconds
► Now speed given= 1 unit
We know speed = Distance / Time
which implies distance = Speed x Time
Hence, the distance becomes 1 x 500 = 500 units.
► Now speed given= 1 unit
We know speed = Distance / Time
which implies distance = Speed x Time
Hence, the distance becomes 1 x 500 = 500 units.
If the error in measurement of radius of sphere is 1% , what will be the error in measurement of volume - a)1%
- b)1/3%
- c)3%
- d)10%
Correct answer is option 'C'. Can you explain this answer?
If the error in measurement of radius of sphere is 1% , what will be the error in measurement of volume
a)
1%
b)
1/3%
c)
3%
d)
10%
|
Geetika Shah answered |
Volume=4πR3/3
ΔV/V×100=3∆R/R×100
=3×1/100×100
=3
∴ Percentage error in volume is 3%
ΔV/V×100=3∆R/R×100
=3×1/100×100
=3
∴ Percentage error in volume is 3%
The order of magnitude of a number expressed in scientific notation is- a)number of decimal places
- b)number of digit before decimal
- c)all digits in the number
- d)power of ten
Correct answer is 'D'. Can you explain this answer?
The order of magnitude of a number expressed in scientific notation is
a)
number of decimal places
b)
number of digit before decimal
c)
all digits in the number
d)
power of ten
|
Lavanya Menon answered |
- To convert a regular number to scientific notation, we first rewrite it as a decimal, then multiply it by a power of 10.
- There is an infinite number of ways to do this for any given number, but we always prefer the one that has only a single digit in front of the decimal point.
Can you explain the answer of this question below: The Van der Waal equation for 1 mole of a real gas is
where P is the pressure, V is the volume, T is the absolute temperature, R is the molar gas constant and a, b are Van dar Waal constants. The dimensions of a are the same as those of
- A:
PV
- B:
PV2
- C:
P2V
- D:
P/V
The answer is B.
The Van der Waal equation for 1 mole of a real gas is
where P is the pressure, V is the volume, T is the absolute temperature, R is the molar gas constant and a, b are Van dar Waal constants. The dimensions of a are the same as those of
PV
PV2
P2V
P/V
|
|
Geetika Shah answered |
The answer is PV2
Solution,
As we know the Vander Waals equation is {P+(a/V2)} (V−b) =RT
Then,
The dimension of a is,
(a/V2) = (P)
Or, a=PV2
Solution,
As we know the Vander Waals equation is {P+(a/V2)} (V−b) =RT
Then,
The dimension of a is,
(a/V2) = (P)
Or, a=PV2
One kilometer is equal to how many miles?- a)0.84
- b)0.5
- c)1.6
- d)0.62
Correct answer is option 'D'. Can you explain this answer?
One kilometer is equal to how many miles?
a)
0.84
b)
0.5
c)
1.6
d)
0.62
|
|
Gaurav Kumar answered |
for an approximate result, divide the length value by 1.609
► One kilometer is equals to 0.62 miles.
1 fermi is equal to:- a)10-10 m
- b)1010 m
- c)1015 m
- d)10-15 m
Correct answer is option 'D'. Can you explain this answer?
1 fermi is equal to:
a)
10-10 m
b)
1010 m
c)
1015 m
d)
10-15 m
|
|
Rohit Shah answered |
One fermi or femtometre is equal 10^-15 m. This unit is used to measure nuclear dimensions.
The number of significant figures in the distance of one light year , 9.4605 × 1015 m is- a)thirty
- b)five
- c)four
- d)three
Correct answer is option 'B'. Can you explain this answer?
The number of significant figures in the distance of one light year , 9.4605 × 1015 m is
a)
thirty
b)
five
c)
four
d)
three
|
|
Preeti Iyer answered |
As the power of 10 is irrelevant in the determination of significant figures hence, the numbers of significant figures are 5.
Can you explain the answer of this question below:After decimal point, number is less than 5 which is to be neglected,then retained number
- A:
gets increased
- B:
get decreased
- C:
remains unchanged
- D:
may decreased
The answer is c.
After decimal point, number is less than 5 which is to be neglected,then retained number
gets increased
get decreased
remains unchanged
may decreased
|
|
Preeti Iyer answered |
In rounding off numbers, the last figure kept should be unchanged if the first figure dropped is less than 5.
Example: If only one decimal is to be kept, then 6.422 becomes 6.4.
Example: If only one decimal is to be kept, then 6.422 becomes 6.4.
According to the principle of homogeneity of dimensions- a)we can subtract similar physical quantities
- b)we can add or subtract similar physical quantities
- c)we can add similar physical quantities
- d)we can add or subtract any physical quantities
Correct answer is option 'B'. Can you explain this answer?
According to the principle of homogeneity of dimensions
a)
we can subtract similar physical quantities
b)
we can add or subtract similar physical quantities
c)
we can add similar physical quantities
d)
we can add or subtract any physical quantities
|
|
Shreya Gupta answered |
The principle of homogeneity is that the dimensions of each the terms of a dimensiional equation on both sides are the same. Any equation or formula involving dimensions (like mass, length, time , temperature electricity) have the terms with same dimensions. This helps us, therefore, to convert the units in one sytem to another system.
The respective number of significant figures for the numbers 23.023, 0.0003 and 21 × 10-3 are- a)5, 1, 2
- b)5, 1, 5
- c)5, 5, 2
- d)4, 4, 2
Correct answer is 'A'. Can you explain this answer?
The respective number of significant figures for the numbers 23.023, 0.0003 and 21 × 10-3 are
a)
5, 1, 2
b)
5, 1, 5
c)
5, 5, 2
d)
4, 4, 2
|
|
Rohan Singh answered |
CORRECT OPTION IS (A).
(i) All the non-zero digits are significant.
(i) All the non-zero digits are significant.
(ii) All the zeros between two non-zero digits are significant, no matter where the decimal point is, if at all.
(iii) If the number is less than 1, the zero(s) on the right of decimal point but to the left of the first non-zero digit are not significant.
(iv) The power of 10 is irrelevant to the determination of significant figures. According to the above rules, 23.023 has 5 significant figures. 0.0003 has 1 significant figures. 2.1 X 10–3 has 2 significant figures.
A dimensionally consistent equation- a)is nearly correct
- b)is always correct
- c)is necessarily correct
- d)is not necessarily correct
Correct answer is option 'D'. Can you explain this answer?
A dimensionally consistent equation
a)
is nearly correct
b)
is always correct
c)
is necessarily correct
d)
is not necessarily correct
|
|
Krishna Iyer answered |
If an equation fails this consistency test, it is proved wrong, but if it passes, it is not proved right.
Thus, a dimensionally correct equation need not be actually an exact (correct) equation, but a dimensionally wrong (incorrect) or inconsistent equation is definitely wrong.
A 2.16 g of a substance occupies 1.5 cm3. Its density to appropriate significant figure is:- a)1.444
- b)1.44
- c)1.4
- d)1.5
Correct answer is option 'D'. Can you explain this answer?
A 2.16 g of a substance occupies 1.5 cm3. Its density to appropriate significant figure is:
a)
1.444
b)
1.44
c)
1.4
d)
1.5
|
|
Hansa Sharma answered |
The multiplication of the numbers:
10.610 × 0.210 = 2.2281
10.610 × 0.210 = 2.2281
Since, the numbers 10.610 and 0.210 have 5 and 3 significant digits, respectively. So, the final result must also have 3 significant digits.
The final answer is 2.23.
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