Answer:
1. Answer: (b) quantities such as length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity
Explanation: In physics, a physical quantity is any physical property that can be quantified, that is, can be measured using numbers. Examples of physical quantities are mass, amount of substance, length, time, temperature, electric current, light intensity, force, velocity, density, and many others.
2. Answer: (c) [ML2T-2]
Explanation: The formula for the kinetic energy is written as:
Kinetic energy = 1/2mv2
= M[LT−1]2
= [ML2T-2]
3. Answer: (a) 105 newton/m2
Explanation: Pressure = F/A
∵106dyne cm−2
=105 Nm−2
4. Answer: (b) FAT2
Explanation: E = KFaAbTc
[ML2T−2] = [MLT−2]a [LT−2]b [T]c
[ML2T−2] = [MaLa+bT−2a−2b+c]
⇒ a = 1,a+b = 2 ⇒ b = 1
and −2a−2b+c=−2 ⇒ c = 2
∴E = KFAT2
5. Answer: (c) work
Explanation: The dimension of kinetic energy is the same as that of work.
6. Answer: (d) Dipole moment, electric flux, electric field
Explanation: Dipole moment = (charge) \(\times\) (distance)
Electric flux = (electric field) \(\times\) (area)
7. Answer: (c) energy
Explanation: electron volt, unit of energy commonly used in atomic and nuclear physics, equal to the energy gained by an electron (a charged particle carrying unit electronic charge) when the electrical potential at the electron increases by one volt.
8. Answer: (b) 216 m3
Explanation: Let length of side of the cube be a then volume of cube = a3
Also, surface area of cube = 6a2
Given, volume of cube = surface area of cube
or a3 = 6a2
⇒ a = 6 m
Thus, volume of the cube = (6)3 =216m3
9. Answer: (b) meter, kilogram, second, coulomb, Kelvin, mole and candela
Explanation: There are seven basic units in the SI system: the meter (m), the kilogram (kg), the second (s), the kelvin (K), the ampere (A), the mole (mol), and the candela (cd).
10. Answer: (c) 60°
Explanation: \(tan\theta=\frac{3}{\sqrt3}=\sqrt3\)
= tan 60°
11. Answer: (a) the difference between the individual measurement and the true value of the quantity cubed
Explanation: Absolute error is simply the amount of physical error in a measurement. For example, if you know a length is 3.535 m + 0.004 m, then 0.004 m is an absolute error. Absolute error is positive. The absolute error is the difference between the measured value and the actual value.
12. Answer: (b) distance
Explanation: A light-year is a measurement of distance and not time (as the name might suggest). A light-year is the distance a beam of light travels in a single Earth year, or 6 trillion miles (9.7 trillion kilometers).
13. Answer: (a) Magnetic flux – weber
Explanation: The unit of the Electric field is N/C or V/m.
The unit of the magnetic field is Weber.
The unit of power is Watt.
The unit of the Capacitance is Farad.
14. Answer: (a) 9192631770 periods of the cesium clock
Explanation: The second is defined as being equal to the time duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental unperturbed ground-state of the caesium-133 atom.
15. Answer: (a) 10–12 farad
Explanation: 1 pF (picofarad, one trillionth (10−12) of a farad) = 0.000000000001 F = 0.001 nF.
16. Answer: (a) pressure
Explanation: The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly 1760 of a standard atmosphere (101325 Pa).
17. Answer: (a) Parallax method
Explanation: Astronomers estimate the distance of nearby objects in space by using a method called stellar parallax, or trigonometric parallax. Simply put, they measure a star's apparent movement against the background of more distant stars as Earth revolves around the sun.
18. Answer: (a) ohm – m
Explanation: The metric unit for specific resistance is the ohm-meter (Ω-m), or ohm-centimeter (Ω-cm)
19. Answer: (a) power
Explanation: Energy per unit time is Power. Hence the dimensions would be of the Power.
20. Answer: (a) Gravitational constant
Explanation: Relative density, refractive index and Poisson ratio all the three are ratios, therefore they are dimensionless constants. Only universal gravitational constant has dimension [M−1L3T2]. Others have no dimensions.
21. Answer: (a) either positive or negative
Explanation: Unlike random error, systematic errors tend to be consistently either positive or negative – because of this, systematic error is sometimes considered to be bias in measurement.
22. Answer: (b) does not depend on the method of measurement
Explanation: The magnitude of any physical quantity clocs not depend on the method of measurement because magnitude is absolute.
23. Answer: (d) None of these
Explanation: Temperature cannot be expressed in the terms of mass, length and time. Temperature is expressed in kelvin.
24. Answer: (a) Quantity of electricity
Explanation: Ampere-hour is the unit of quantity of electricity or quantity of electric charge.
25. Answer: (a) Distance
Explanation: The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,000 astronomical units (au), i.e. 30.9 trillion kilometres (19.2 trillion miles).
Click here to practice MCQ Questions for Units and Measurements class 11