Download App

JEE physics MCQ

Units, Dimensions and Measurement · CBSE STD 12 Science (CBSE - English Medium). 293 questions.

Questions · Page 1 of 6

MCQ

🎯

Test yourself on this topic

50 questions · timed · auto-graded

MCQ 11 Mark
The dimensions of electric potential are
  • ✓
    $\left[M L^2 T^{-2} Q^{-1}\right]$
  • B
    $\left[M L T^{-2} Q^{-1}\right]$
  • C
    $\left[M L^2 T^{-1} Q\right]$
  • D
    $\left[M L^2 T^{-2} Q\right]$
Answer
Correct option: A.
$\left[M L^2 T^{-2} Q^{-1}\right]$
(a) $\quad V=\frac{W}{Q}=\left[M L^2 T^{-2} Q^{-1}\right]$
View full question & answer→
MCQ 21 Mark
If the velocity of light $$, gravitational constant $(G)$ and Planck's constant (h) are chosen as fundamental units, then the dimensions of mass in new system is
  • A
    $c^{1 / 2} G^{1 / 2} h^{1 / 2}$
  • B
    $c^{1 / 2} G^{1 / 2} h^{-1 / 2}$
  • ✓
    $c^{1 / 2} G^{-1 / 2} h^{1 / 2}$
  • D
    $c^{-1 / 2} G^{1 / 2} h^{1 / 2}$
Answer
Correct option: C.
$c^{1 / 2} G^{-1 / 2} h^{1 / 2}$
(c) Let $m \propto C^x G^y h^z$By substituting the following dimensions :$C]=L T^{-1} ;[G]=\left[M^{-1} L^3 T^{-2}\right] \text { and }[h]=\left[M L^2 T^{-1}\right]$Nowcomparing both sides we will get$x=1 / 2 ; y=-1 / 2, z=+1 / 2$So $m \propto c^{1 2} G^{-1 / 2} h^{1 / 2}$
View full question & answer→
MCQ 31 Mark
Dimensions of luminous flux are
  • A
    $M L^2 T^{-2}$
  • ✓
    $M L^2 T^{-3}$
  • C
    $M L^2 T^{-1}$
  • D
    $M L T^{-2}$
Answer
Correct option: B.
$M L^2 T^{-3}$
(b)
View full question & answer→
MCQ 41 Mark
Which of the following is not a unit of time
  • A
    Leap year
  • B
    Micro second
  • C
    Lunar month
  • ✓
    Light year
Answer
Correct option: D.
Light year
(d) 1 lightyear $=9.46 \times 10^{15}$ meter
View full question & answer→
MCQ 51 Mark
The correct value of $0^{\circ} C$ on the Kelvin scale is
  • ✓
    $273.15 K$
  • B
    $272.85 K$
  • C
    $273 K$
  • D
    $273.2 K$
Answer
Correct option: A.
$273.15 K$
(a) $K=C+273.15$
View full question & answer→
MCQ 61 Mark
Candela is the unit of
  • A
    Electric intensity
  • ✓
    Luminous intensity
  • C
    Sound intensity
  • D
    None of these
Answer
Correct option: B.
Luminous intensity
(b)
View full question & answer→
MCQ 71 Mark
The dimensions of inter atomic force constant are
  • ✓
    $M T^{-2}$
  • B
    $M L T^{-1}$
  • C
    $M L T^{-2}$
  • D
    $M L^{-1} T^{-1}$
Answer
Correct option: A.
$M T^{-2}$
(a)
$K=Y \times r_0=\left[M L^{-1} T^{-2}\right] \times[L]=\left[M T^{-2}\right]$.
$Y=\text { Young's modulus and } r_0=\text { Interatomic distance }$
View full question & answer→
MCQ 81 Mark
Which is not a unit of electric field
  • A
    $NC ^{-1}$
  • B
    $V m^{-1}$
  • ✓
    $J C^{-1}$
  • D
    $J C^{-1} m^{-1}$
Answer
Correct option: C.
$J C^{-1}$
(c)
View full question & answer→
MCQ 91 Mark
Match List-l with List-ll and select the correct answer using the codes given below the lists
List-1 List-ll
I. Joule A. Henry $\times$ Amp/sec
II. Watt B. Farad $\times$ Volt
III. Volt C. Coulomb $\times$ Volt
IV. Coulomb D. Oersted $\times cm$
E. Amp $\times$ Gauss
F. $A m p^2 \times Ohm$
  • A
    $I-A, I I-F, I I I-E, I V-D$
  • ✓
    $I-C, I I-F, I I I-A, I V-B$
  • C
    $I-C, I I-F, I I I-A, I V-E$
  • D
    $I-B, I I-F, I I I-A, I V-C$
Answer
Correct option: B.
$I-C, I I-F, I I I-A, I V-B$
(b)
View full question & answer→
MCQ 101 Mark
Which of the following is not equal to watt
  • A
    Joule/second
  • B
    Ampere $\times$ volt
  • C
    $($ Ampere $) \times$ ohm
  • ✓
    Ampere/volt
Answer
Correct option: D.
Ampere/volt
(d) Watt=Joule/second $=$ Ampere $\times$ volt $=$ Ampere $\times O$ hm
View full question & answer→
MCQ 111 Mark
In which of the following systems of unit, Weber is the unit of magnetic flux
  • A
    CGS
  • B
    MKS
  • ✓
    $Sl$
  • D
    None of these
Answer
Correct option: C.
$Sl$
(c)
View full question & answer→
MCQ 121 Mark
The unit of specific resistance is
  • A
    $Ohm / cm ^2$
  • B
    $Ohm / cm$
  • ✓
    $Ohm - cm$
  • D
    $( Ohm - cm )^{-1}$
Answer
Correct option: C.
$Ohm - cm$
(c) $R=\rho \frac{L}{A} \Rightarrow \rho=\frac{R A}{L}=o h m \times c m$
View full question & answer→
MCQ 131 Mark
Universal time is based on
  • A
    Rotation of the earth on its axis
  • B
    Earth's orbital motion around the earth
  • ✓
    Vibrations of cesium atom
  • D
    Oscillations of quartz crystal
Answer
Correct option: C.
Vibrations of cesium atom
(c) According to the definition.
View full question & answer→
MCQ 141 Mark
Oersted is a unit of
  • A
    Dip
  • ✓
    Magnetic intensity
  • C
    Magnetic moment
  • D
    Pole strength
Answer
Correct option: B.
Magnetic intensity
(b) 1 Oerstead $=1$ Gauss $=10^{-4}$ Tesla
View full question & answer→
MCQ 151 Mark
One nanometre is equal to
  • A
    $10^9 mm$
  • B
    $10^{-6} cm$
  • ✓
    $10^{-7} cm$
  • D
    $10^{-9} cm$
Answer
Correct option: C.
$10^{-7} cm$
(c) $1 \mathrm{~nm}=10^{-9} \mathrm{~m}=10^{-7} \mathrm{~cm}$
View full question & answer→
MCQ 161 Mark
Parsec is a unit of
  • ✓
    Distance
  • B
    Velocity
  • C
    Time
  • D
    Angle
Answer
Correct option: A.
Distance
(a) Astronomical unit of distance.
View full question & answer→
MCQ 171 Mark
The Sl unit of momentum is
  • A
    $\frac{k g}{m}$
  • ✓
    $\frac{ kg \cdot m }{ sec }$
  • C
    $\frac{ kg \cdot m ^2}{ sec }$
  • D
    $k g \times N e w t o n$
Answer
Correct option: B.
$\frac{ kg \cdot m }{ sec }$
(b) $\quad m v=k g\left(\frac{m}{\mathrm{sec}}\right)$
View full question & answer→
MCQ 181 Mark
The dimension of $\frac{1}{\sqrt{\varepsilon_0 \mu_0}}$ is that of
  • ✓
    Velocity
  • B
    Time
  • C
    Capacitance
  • D
    Distance
Answer
Correct option: A.
Velocity
(a) $\frac{1}{\sqrt{\varepsilon_0 \mu_0}}=C=$ velocity of light
View full question & answer→
MCQ 191 Mark
$1 eV$ is
  • A
    Same as one joule
  • ✓
    $1.6 \times 10^{-19} J$
  • C
    $1 V$
  • D
    $1.6 \times 10^{-19} C$
Answer
Correct option: B.
$1.6 \times 10^{-19} J$
(b) $1 \mathrm{eV}=1.6 \times 10^{-19}$ coulomb $\times 1$ volt $=1.6 \times 10^{-19}\mathrm{~J}$.
View full question & answer→
MCQ 201 Mark
If $u_1$ and $u_2$ are the units selected in two systems of measurement and $n_1$ and $n_2$ their numerical values, then
  • ✓
    $n_1 u_1=n_2 u_2$
  • B
    $n_1 u_1+n_2 u_2=0$
  • C
    $n_1 n_2=u_1 u_2$
  • D
    $\left(n_1+u_1\right)=\left(n_2+u_2\right)$
Answer
Correct option: A.
$n_1 u_1=n_2 u_2$
(a) Physical quantity $(p)=$ Numerical value $(n) \times$ Unit $(u)$ If physicalquantity remains constant then $n \propto 1 / u \therefore n u=n u$
View full question & answer→
MCQ 211 Mark
The unit of angular acceleration in the SI system is
  • A
    $Nkg ^{-1}$
  • B
    $m s^{-2}$
  • ✓
    $rads ^{-2}$
  • D
    $m kg ^{-1} K$
Answer
Correct option: C.
$rads ^{-2}$
(c) Angular acceleration $=\frac{\text { Angular vdocity }}{\text { Time=\frac{\mathrm{rad}}{\mathrm{sec}^2}$
View full question & answer→
MCQ 221 Mark
Ampere-hour is a unit of
  • ✓
    Quantity of electricity
  • B
    Strength of electric current
  • C
    Power
  • D
    Energy
Answer
Correct option: A.
Quantity of electricity
(a) Charge $=$ current $\times$ time
View full question & answer→
MCQ 231 Mark
The binding energy of a nucleon in a nucleus is of the order of a few
  • A
    $eV$
  • B
    Ergs
  • ✓
    $MeV$
  • D
    Volts
Answer
Correct option: C.
$MeV$
(c)
View full question & answer→
MCQ 261 Mark
Which relation is wrong
  • A
    1 Calorie $=4.18$ Joules
  • B
    $1 A=10^{-10} m$
  • C
    $1 MeV =1.6 \times 10^{-13}$ Joules
  • ✓
    1 Newton $=10^{-5}$ Dynes
Answer
Correct option: D.
1 Newton $=10^{-5}$ Dynes
(d) 1 Newton $=10$ Dyne
View full question & answer→
MCQ 271 Mark
A physical quantity is measured and its value is found to be $n u$ where $n=$ numerical value and $u=$ unit. Then which of the following relations is true
  • A
    $n \propto u^2$
  • B
    $n \propto u$
  • C
    $n \propto \sqrt{u}$
  • ✓
    $n \propto \frac{1}{u}$
Answer
Correct option: D.
$n \propto \frac{1}{u}$
(d) $P=n u \therefore n \propto \frac{1}{u}$
View full question & answer→
MCQ 281 Mark
Out of the following which pair of quantities do not have same dimensions
  • A
    Planck's constant and angular momentum
  • B
    Work and energy
  • C
    Pressure and Young's modulus
  • ✓
    Torque \& moment of inertia
Answer
Correct option: D.
Torque \& moment of inertia
(d) Torque $=\left[M L^2 T^{-2}\right]$, Moment of inertia $=\left[M L^2\right]$
View full question & answer→
MCQ 291 Mark
$M L^3 T^{-1} Q^{-2}$ is dimension of
  • ✓
    Resistivity
  • B
    Conductivity
  • C
    Resistance
  • D
    None of these
Answer
Correct option: A.
Resistivity
(a)$\text { Resistivity }[\rho]=\frac{[R] \cdot[A]}{[l]}$   where $[R]=\left[M L^2 T^{-1} Q^{-2}\right]$
$\therefore[\rho]=\left[M L^3 T^{-1} Q^{-2}\right]$
View full question & answer→
MCQ 301 Mark
Dyne/ $/ cm$ is not a unit of
  • A
    Pressure
  • B
    Stress
  • ✓
    Strain
  • D
    Young's modulus
Answer
Correct option: C.
Strain
(c)
View full question & answer→
MCQ 311 Mark
The dimension of quantity $(L / R C V)$ is
  • A
    $[A]$
  • B
    $\left[A^2\right]$
  • ✓
    $\left[A^{-1}\right]$
  • D
    None of these
Answer
Correct option: C.
$\left[A^{-1}\right]$
(c) $\frac{L}{R C V}=\left[\frac{L}{R}\right] \frac{1}{C V}=\frac{T}{Q}=\left[A^{-1\right]$
View full question & answer→
MCQ 321 Mark
The dimensions of universal gas constant is
  • ✓
    $\left[M L^2 T^{-2} \theta^{-1}\right]$
  • B
    $\left[M^2 L T^{-2} \theta\right]$
  • C
    $\left[M L^3 T^{-1} \theta^{-1}\right]$
  • D
    None of these
Answer
Correct option: A.
$\left[M L^2 T^{-2} \theta^{-1}\right]$
(a) $\because R=\frac{P V}{T}=\left[\frac{M L^{-1} T^{-2} \times L^3}{\theta}\right]=\left[M L^2T^{-2} \theta^{-1}\right]$
View full question & answer→
MCQ 331 Mark
The number of significant figures in all the given numbers 25.12 , $2009,4.156$ and $1.217 \times 10^{-4}$ is
  • A
    1
  • B
    2
  • C
    3
  • ✓
    4
Answer
Correct option: D.
4
(d) The number of significant figures in all of the given number is 4.
View full question & answer→
MCQ 341 Mark
The unit of Young's modulus is
  • A
    $N m^2$
  • ✓
    $N m^{-2}$
  • C
    $Nm$
  • D
    $N m^{-1}$
Answer
Correct option: B.
$N m^{-2}$
(b)
View full question & answer→
MCQ 351 Mark
Unit of surface tension is
  • ✓
    $Nm ^{-1}$
  • B
    $N m^{-2}$
  • C
    $N^2 m^{-1}$
  • D
    $Nm ^{-3}$
Answer
Correct option: A.
$Nm ^{-1}$
(a) $T=\frac{F}{l}=\mathrm{Nm}^{-1}$
View full question & answer→
MCQ 361 Mark
Which does not has the same unit as others
  • A
    Watt-sec
  • B
    Kilowatt-hour
  • C
    $eV$
  • ✓
    J-sec
Answer
Correct option: D.
J-sec
(d) Joule-sec is the unit of angular momentum where as other units are of energy.
View full question & answer→
MCQ 371 Mark
Position of a body with acceleration ' $a$ ' is given by $x=K a^m t^n$, here $t$ is time. Find dimension of $m$ and $n$.
  • A
    $m=1, n=1$
  • ✓
    $m=1, n=2$
  • C
    $m=2, n=1$
  • D
    $m=2, n=2$
Answer
Correct option: B.
$m=1, n=2$
(b) As $x=K a^m \times t^n $
$\left[M^0 L T^0 \right] =\left[LT^{-2}\right]^m[T]^n=\left[L^m T^{-2 m+n}\right] $
$\therefore m=1 \text { and }-2 m+n=0 \Rightarrow n=2 .$
View full question & answer→
MCQ 381 Mark
The dimensions of $K$ in the equation $W=\frac{1}{2} K x^2$ is
  • ✓
    $M^1 L^0 T^{-2}$
  • B
    $M^0 L^1 T^{-1}$
  • C
    $M^1 L^1 T^{-2}$
  • D
    $M^1 L^0 T^{-1}$
Answer
Correct option: A.
$M^1 L^0 T^{-2}$
(a) $W=\frac{1}{2} k x^2 \Rightarrow[k]=\frac{[W]}{\left[x^2\right]}=\left[\frac{M L^2 T^{-2}}{L^2}\right]=\left[M T^{-2}\right]$
View full question & answer→
MCQ 391 Mark
An object is moving through the liquid. The viscous damping force acting on it is proportional to the velocity. Then dimension of constant of proportionality is
  • A
    $M L^{-1} T^{-1}$
  • B
    $M L T^{-1}$
  • C
    $M^0 L T^{-1}$
  • ✓
    $M L^0 T^{-1}$
Answer
Correct option: D.
$M L^0 T^{-1}$
(d) $F \propto v \Rightarrow F=k v \Rightarrow[k]=\left[\frac{F}{v}\right]=\left[\frac{M L T^{-2}}{L T^{-1}}\right]=\left[M T^{-1}\right]$
View full question & answer→
MCQ 401 Mark
Which is different from others by units
  • A
    Phase difference
  • B
    Mechanical equivalent
  • C
    Loudness of sound
  • ✓
    Poisson's ratio
Answer
Correct option: D.
Poisson's ratio
(d) Poission ratio is a unitless quantity.
View full question & answer→
MCQ 411 Mark
Match List-l with List-ll and select the correct answer by using the codes given below the lists
List-I List-ll
Distance between earth and stars 1. Microns
Inter-atomic distance in a solid 2. Angstroms
Size of the nucleus 3. Light years
Wavelength of infrared laser 4. Fermi
5. Kilometres
  • A
    $\begin{array}{lllll}\text { } & 5 & 4 & 2 & 1\end{array}$
  • ✓
    $\begin{array}{lllll}\text { } & 3 & 2 & 4 & 1\end{array}$
  • C
    $\begin{array}{lllll}\text { } & 5 & 2 & 4 & 3\end{array}$
  • D
    $\begin{array}{lllll}\text { } & 3 & 4 & 1 & 2\end{array}$
Answer
Correct option: B.
$\begin{array}{lllll}\text { } & 3 & 2 & 4 & 1\end{array}$
(b)
View full question & answer→
MCQ 421 Mark
Which of the following is not represented in correct unit
  • A
    $\frac{\text { Stress }}{\text { Strain }}=N / m^2$
  • B
    Surface tension $=N / m$
  • ✓
    Energy $=k g-m / sec$
  • D
    Pressure $=N / m^2$
Answer
Correct option: C.
Energy $=k g-m / sec$
(c) Unit of energy will be $\mathrm{kg}-\mathrm{m}^2 / \mathrm{sec}^2$
View full question & answer→
MCQ 431 Mark
The velocity of a freely falling body changes as $g^p h^q$ where $g$ is acceleration due to gravity and $h$ is the height. The values of $p$ and $q$ are
  • A
    $1, \frac{1}{2}$
  • ✓
    $\frac{1}{2}, \frac{1}{2}$
  • C
    $\frac{1}{2}, 1$
  • D
    1,1
Answer
Correct option: B.
$\frac{1}{2}, \frac{1}{2}$
(b) $v \propto g^p h^q$ (given)By substituting the dimension of each quantity and comparing the powers in both sides we get $\left[L T^{-1}\right]=\left[L T^{-2}\right]^p[L]^q$$\Rightarrow p+q=1,-2 p=-1, \therefore p=\frac{1}{2}, q=\frac{1}{2}$
View full question & answer→
MCQ 471 Mark
The dimensions of shear modulus are
  • A
    $M L T^{-1}$
  • B
    $M L^2 T^{-2}$
  • ✓
    $M L^{-1} T^{-2}$
  • D
    $M L T^{-2}$
Answer
Correct option: C.
$M L^{-1} T^{-2}$
(c) Shear modulus $=\frac{\text { Shearing stress }}{\text { Shearing strain }}=\frac{F}{A \theta}=\left[M L^{-1} T^{-2}\right]$
View full question & answer→
MCQ 481 Mark
The units of angular momentum are
  • A
    $kg \rightarrow m^2 / s ^2$
  • ✓
    Joule-s
  • C
    Joule/s
  • D
    $k g \rightarrow m-s^2$
Answer
Correct option: B.
Joule-s
(b)
View full question & answer→
MCQ 491 Mark
The units of modulus of rigidity are
  • A
    $N-m$
  • B
    $N / m$
  • C
    $N-m^2$
  • ✓
    $N / m^2$
Answer
Correct option: D.
$N / m^2$
(d)
View full question & answer→
MCQ 501 Mark
If $R$ and $L$ represent respectively resistance and self inductance, which of the following combinations has the dimensions of frequency
  • ✓
    $\frac{R}{L}$
  • B
    $\frac{L}{R}$
  • C
    $\sqrt{\frac{R}{L}}$
  • D
    $\sqrt{\frac{L}{R}}$
Answer
Correct option: A.
$\frac{R}{L}$
(a) $\frac{R}{L}=\frac{V / I}{V \times T / I}=\frac{1}{T}=$ Frequency
View full question & answer→
Generate Paper FreeAll Units, Dimensions and Measurement topics
MCQ - JEE physics STD 12 Science Questions - Vidyadip