Tag: measurement of distance

Questions Related to measurement of distance

A star is $1.45\ parsec$ light years away. How much parallax would this star show when viewed from two locations of the earth six months apart in its orbit around the sun?

physics motion and measurement measuring length measurement of small and large distances measurement of distance

  1. $2\ Parsec$

  2. $0.725\ Parsec$

  3. $1.45\ Parsec$

  4. $2.9\ Parsec$

Show answer
Correct Option: A
Explanation:

One light year $=$ speed of light $\times$ one year

or $1 ly=3\times 10^8\times (24\times 3600)=94608\times 10^{11} m$
So, $4.29 ly=4.29\times (94608\times 10^{11})=4.058\times 10^{16} m$
As $1 $ parsec $=3.08\times 10^{16} m$
(Parsec is a unit of length used to measure large distances to objects outside our Solar System)
Thus, $4.29 ly=\dfrac{4.058\times 10^{16}}{3.08\times 10^{16}}=1.32$ parsec
Now angular displacement , $\theta=\dfrac{d}{D}$
where $d=$ diameter of earth's orbit $= 3\times 10^{11} m$ and 
$D=$ distance of star from the earth $=4.058\times 10^{16} m$
So, $\theta=\dfrac{3\times 10^{11}}{4.058\times 10^{16}}=7.39\times 10^{-6}$ rad
As $1 sec=4.85\times 10^{-6} rad$ so, $7.39\times 10^{-6} rad=\dfrac{7.39\times 10^{-6}}{4.85\times 10^{-6}}=1.52 sec$

Which of the following is not unit of length?

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. angstrom

  2. fermi

  3. barn

  4. parsec

Show answer
Correct Option: C
Explanation:

Angstrom, fermi and parsec are the units of length whereas barn is the unit of nuclear cross-section. 

Which of the following is the smallest unit?

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. millimetre

  2. angstrom

  3. fermi

  4. metre

Show answer
Correct Option: C
Explanation:
$1 \ mm = 10^{-3}\ m$
 $1 \ \overset{o}{A} = 10^{-10} \  m$;
$1 \ fm =10^{-15}\  m$
Among the given units fermi is the smallest unit.
Hence the correct option is $(C)$

Which of the following system of units is not based on unit of mass, length and time?

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. CGS

  2. FPS

  3. MKS

  4. SI

Show answer
Correct Option: D
Explanation:
The SI unit system is not based on only mass, length and time alone. 
This unit system is consists of seven fundamental units which can be given as mass, length, time, temperature, luminous intensity, mole and current.
The correct answer is option $(D)$

Match the Column I with Column II.

Column I Column II
(A) Distance between earth and sun (p) Micron
(B) Interatomic distance in a solid (q) Fermi
(C) Size of a nucleus (r) Light year
(D) Wavelength of infrared laser (s) Angstrom
physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. A - p, B - q, C - r, D - s

  2. A - r, B - s, C - q, D - p

  3. A - q, B - p, C - s, D - r

  4. A - s. B - r, C - p, D - q

Show answer
Correct Option: B
Explanation:

Distance between earth and sun - Light year
Interatomic distance in a solid - Angstrom
Size of a nucleus - Fermi
Wavelength of infrared laser - Micron

Match the Column I with Column II

Column I(Physical quantity) Column II(Name of unit)
(A) Conductance (p) gray
(B) Magnetic induction (q) lumen
(C) Absorbed dose (r) tesla
(D) Luminous flux (s) siemens
physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. A - s, B - r, C - p, D - q.

  2. A - p, B - q, C - r, D - s.

  3. A - q, B - p, C - s, D - r.

  4. A - r, B - s, C - p, D - q.

Show answer
Correct Option: A
Explanation:

1) Conductance (G) is reciprocal of resistance (R).

$\therefore G=\dfrac{1}{R}$
$\therefore G=\dfrac{I}{V}$      $\left[\therefore \text{since}\,R=\dfrac{V}{I}\right]$
And its Unit is Siemens (S)
2) When an emf [electromotive force] is induced in a circuit due to change in the magnetic flux associated with the circuit is called Magnetic Induction.
$B=\dfrac{F}{q\,v\,\sin\theta}$
Unit is Tesla
3) Absorbed Dose (D) is the amount of energy abdorbed per unit mass of tissue.
Unit is GRAY (Gy)
4) Luminous flux is the measurement of brightness of a light source in terms of energy emitted.
SI unit is Lumen.

What is the value of $1 \ m $ in $\mu$ (micron)?

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. $10^5$

  2. $10^6$

  3. $10^9$

  4. $10^{12}$

Show answer
Correct Option: B
Explanation:

Answer is B

$1\ m=10^{6}\mu $
The micrometer is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria and is also commonly used in plastics manufacturing.

$5800 \mathring A$ in nm will be?

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. 58

  2. 5.8

  3. 580

  4. 0.58

Show answer
Correct Option: C
Explanation:

We know that $1{\buildrel _{\circ}\over{\mathrm{A}}}=10^{-10} m$

$1$ nanometer or $1\ nm =$$10^{-9}m$
So, we get $1{\buildrel _{\circ}\over{\mathrm{A}}}=0.1 nm$
$5800{\buildrel _{\circ}\over{\mathrm{A}}}=0.1\times 5800\ nm= 580\ nm$

Convert $1$ $ \displaystyle g/cm^{3} $ to $\displaystyle kg/m^{3} $

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. 1000

  2. 100

  3. 0.1

  4. 10

Show answer
Correct Option: A
Explanation:

We know that  $1 \ g = \dfrac{1}{1000} \ kg$
Also,  $1\ cm = \dfrac{1}{100} \ m$
Thus   $1g/cm^3 = 1 \ g\times\dfrac{1  \ kg}{1000 \ g}\times \dfrac{1}{1 \ cm^3}\times \dfrac{(100)^3 \ cm^3}{1 \ m^3} = 1000 \ kg/m^3$

One centimetre is equal to

physics learning how to measure measurement of small and large distances measurement of distance unit of fundamental quantities

  1. 5 mm

  2. 10 mm

  3. 15 mm

  4. None of these

Show answer
Correct Option: B
Explanation:

We know that:

$ 1\ cm = 10\ mm$