List of top Physics Questions on physical world

The quantities $x=\frac{1}{\sqrt{\mu_{0} \epsilon_{0}}}, y=\frac{E}{B}$ and $z =\frac{1}{ CR }$ are defined where C - capacitance R - Resistance, l - length, E - Electric field, B - magnetic field and $\epsilon_{0}, \mu_{0},$ - free space permittivity and permeability respectively. Then :

Dimensional formula for thermal conductivity is (here $K$ denotes the temperature)

A screw gauge has $50$ divisions on its circular scale. The circular scale is $4 $ units ahead of the pitch scale marking, prior to use. Upon one complete rotation of the circular scale, a displacement of $0.5\, mm$ is noticed on the pitch scale. The nature of zero error involved, and the least count of the screw gauge, are respectively :

Amount of solar energy received on the earth's surface per unit area per unit time is defined a solar constant. Dimension of solar constant is:

If momentum $ (P)$, area $(A)$ and time $(T)$ are taken to be the fundamental quantities then the dimensional formula for energy is :

A quantity $x$ is given by $(IFv^2 / WL^{4})$ in terms of moment of inertia $I, $ force $ F$, velocity $v ,$ work $W$ and Length $L$. The dimensional formula for $x$ is same as that of :

If speed $V$, area $A$ and force $F$ are chosen as fundamental units, then the dimension of Young's modulus will be :

The density of a material in SI units is $128 \; kg \; m^{-3}$. In certain units in which the unit of length is $25\, cm$ and the unit of mass is $50\, g$, the numerical value of density of the material is :

In a simple pendulum experiment for determination of acceleration due to gravity (g), time taken for $20$ oscillations is measured by using a watch of $1$ second least count. The mean value of time taken comes out to be $30\, s$. The length of pendulum is measured by using a meter scale of least count $1\, mm$ and the value obtained is $55.0\, cm$. The percentage error in the determination of $g$ is close to :

If speed $(V)$, acceleration $(A)$ and force $(F)$ are considered as fundamental units, the dimension of Young's modulus will be :

Let us consider a system of units in which mass and angular momentum are dimensionless. If length has dimension of L, which of the following statement(s) is/are correct?

In a screw gauge, $5$ complete rotations of the screw cause it to move a linear distance of $0.25\, cm$. There are $100$ circular scale divisions. The thickness of a wire measured by this screw gauge gives a reading of $4$ main scale divisions and $30$ circular scale divisions. Assuming negligible zero error, the thickness of the wire is :

Order of magnitude of a physical quantity is the

Consider the following statements about the four fundamental forces in nature (i) The strong nuclear force binds protons and neutrons in a nucleus (ii) The strong nuclear force is about $ 10^{3} $ times the electromagnetic force in strength (iii) The weak nuclear force is the weakest of all the four fundamental forces (iv) The range of the weak nuclear is about $ 10^{-16}\, m $ . The correct statement (s) is (are)

In electromagnetic theory, the electric and magnetic phenomena are related to each other. Therefore, the dimensions of electric and magnetic quantities must also be related to each other. In the questions below, $[E]$ and [ The relation between $[\varepsilon_0]$ and $[\mu_0]$ is

In an experiment to measure the speed of sound by a resonating air column, a tuning fork of frequency $500 \, Hz$ is used. The length of the air column is varied by changing the level of water in the resonance tube. Two successive resonances are heard at air columns of length $50.7 \, cm $ and $83.9 \, cm$. Which of the following statements is (are) true?

If the measurement errors in all the independent quantities are known, then it is possible to determine the error in any dependent quantity. This is done by the use of series expansion and truncating the expansion at the first power of the error. For example, consider the relation $z = x/y$. If the errors in $x ,y $ and $z$ are $\Delta x, \Delta y$ and $\Delta z$, respectively, then $z \pm \Delta z = \frac{x \pm \Delta x}{y \pm \Delta y} = \frac{x}{y} \left( 1 \pm \frac{\Delta x}{x} \right) \left( 1 \pm \frac{\Delta y}{y} \right)^{-1}$. The series expansion for $\left( 1 \pm \frac{\Delta y}{y} \right)^{-1}$, to first power in $\Delta y/y $. is $1 \mp (\Delta y / y )$. The relative errors in independent variables are always added. So the error in $z$ will be $\Delta z = z \left( \frac{\Delta x}{x} + \frac{\Delta y}{y} \right)$ . The above derivation makes the assumption that $\Delta powers of these quantities are neglected. In an experiment the initial number of radioactive nuclei is $3000$. It is found that $1000 \pm 40 $ nuclei decayed in the first 1.0 s. For $|x| < < 1$, ln $(1 + x) = x$ up to first power in $x$. The error $\Delta \lambda$, in the determination of the decay constant $\lambda$, in $s^{-1}$, is

A physical quantity $P$ is described by the relation $P = a^{1/2} b^2 c^3 d^{-4} $ If the relative errors in the measurement of $a, b, c$ and $d$ respectively, are $2\%, 1\%, 3\%$ and $5\%$, then the relative error in $P$ will be :

A person measures the depth of a well by measuring the time interval between dropping a stone and receiving the sound of impact with the bottom of the well. The error in his measurement of time is $\delta T =0.01$ seconds and he measures the depth of the well to be $L =20$ meters. Take the acceleration due to gravity $g =10\, ms ^{-2}$ and the velocity of sound is $300\, ms ^{-1}$. Then the fractional error in the measurement, $\delta L / L$, is closest to

A body $ A $ thrown vertical upwards with a velocity v reaches a height of $ 200\, m $ . Another body $ B $ whose mass is twice that of $ A $ is thrown with a velocity $ 2v $ . Find the maximum height reached by $ B $ .

Consider an expanding sphere of instantaneous radius

The velocity of a transverse wave in a string is directly proportional to $ \sqrt T $ and inversely proportional to $ \sqrt \mu $ . In a measurement, the mass applied at the end of string is $ 3.0 \,g $ , length of string is $ 1 \,m $ and mass of string is $ 5 \,g $ . If possible error in measuring mass is $ 0.1 \,g $ and that of length is $ 1 \,mm $ , the percentage error in measurement of velocity is

$A, B, C$ and $D$ are four different physical quantities having different dimensions. None of them is dimensionless. But we know that the equation $AD = C$ ln $(BD)$ holds true. Then which of the combination is not a meaningful quantity ?

A screw gauge with a pitch of $0.5\, mm$ and a circular scale with $50$ divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the $45^{th}$ division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is $0.5\, mm$ and the $25^{th}$ division coincides with the main scale line ?

A student measures the time period of $100$ oscillations of a simple pendulum four times. The data set is $90\, s, 91\, s, 95\, s$ and $92\, s$. If the minimum division in the measuring clock is $1 \,s$, then the reported mean time should be :