List of top Physics Questions

If numerical aperture of a microscope is increased then its

The ratio of magnetic fields due to a bar magnet at the two axial points $P_1$ and $P_2$ which are separated from each other by $10 \,cm$ is 25 : 2. Point $P_1$ is situated at 10 cm from the centre of the magnet. Magnetic length of the bar magnet is (Points $P_1$ and $P_2$ are on the same side of magnet and distance of $P_2$ from the centre is greater than distance of $P_1$ from the centre of magnet)

The increase in energy of a metal bar of length 'L' and cross-sectional area 'A' when compressed with a load 'M' along its length is (Y = Young�s modulus of the material of metal bar)

The angle made by incident ray of light with the reflecting surface is called

A square frame $ABCD$ is formed by four identical rods each of mass 'm' and length 'l' This frame is in $XY$ -plane such that side $AB$ coincides with $X$-axis and side $AD$ along $Y$-axis. The moment of inertia of the frame about $X$-axis is

If the half life of a radioactive nucleus is $3$ days, nearly what fraction of the initial number of nuclei will decay on the $3$rd day ? (Given that $\sqrt[3]{0.25} \approx 0.63)$)

How the linear velocity ?$v$? of an electron in the Bohr orbit is related to its quantum number ?$n$? ?

The force between the plates of a parallel plate capacitor is proportional to charge on it. Electric force is equal to charge per unit area.

Current sensitivity of a moving coil galvanometer is $5 \,div/mA$ and its voltage sensitivity (angular deflection per unit voltage applied) is $20 \,div/V$. The resistance of the galvanometer is

The only force acting on a $ 2 \,kg $ body that is moving in $ xy- $ plane has a magnitude of $ 5\, N $ . The body initially has a velocity of $ 4 \,m/s $ in the positive $ x $ -direction. Some time later, the body has a velocity of $ 6 \,m/s $ in the positive $ y- $ direction. The work done on the body by the $ 5 \,N $ force during this time is

Centre of mass of a uniform ring of radius R will be at a position

Which one of the following statements is incorrect ?

A stationary source (see figure) emits sound waves of frequency $f$ towards a stationary wall. If an observer moving with speed u in a direction perpendicular to the wall measures a frequency $f' = \frac{11}{8} f $ at the instant shown, then $u$ is related to the speed of sound $V_S$ as

A rectangular wire loop with length a and width b lies in the xy-plane as shown. Within the loop, there is a time dependent magnetic field given by $B = c [( x \cos \omega t ) \hat{ i }+( y \sin \omega t ) \hat{ k }]$ Here, $C$ and $\omega$ are constants. The magnitude of emf induced in the loop as a function of time is

The basic idea of MASER was first given by

Figure shows a potentiometer. Length of the potentiometer wire $ AB $ is $ 100 \,cm $ and its resistance is $ 100\, \Omega $ . $ EMF $ of the battery $ E $ is $ 2 V $ . A resistance $ R $ of $ 50 \Omega $ draws current from the potentiometer. What is the voltage across $ R $ when the sliding contact $ C $ is at the mid-point of $ AB $ ?

Find R between A and B.

For a copper block, find the electric field which can give on an average $ 1 \,eV $ energy to a conduction electron. (The mean free path of conduction electrons in copper is given as $ 4 \times 10^{-8}\, m $ )

Figure shows a potentiometer. Length of the potentiometer wire $ AB $ is $ 100 \,cm $ and its resistance is $ 100\, \Omega $ . $ EMF $ of the battery $ E $ is $ 2 V $ . A resistance $ R $ of $ 50 \Omega $ draws current from the potentiometer. What is the voltage across $ R $ when the sliding contact $ C $ is at the mid-point of $ AB $ ?

Four resistors $100 \, \Omega , 200 \, \Omega, 300 \, \Omega$ and $400 \, \Omega$ are connected to form four sides of a square. The resistors can be connected in any order. What is the maximum possible equivalent resistance across the diagonal of the square ?

What will be current through the $200 \, \Omega$ resistor in the given circuit a long time after the switch �K� is made on ?

In a potentiometer experiment of a cell of emf $1.25\, V$ gives balancing length of $30\, cm$. If the cell is replaced by another cell, balancing length is found to be $40\, cm$. What is the emf of second cell ?

In the circuit shown, the current through the 5 O resistor is

A current flows in a conductor only when there is an electric field within the conductor. The drift velocity of electron in presence of electric field decreases.