List of top Physics Questions

What is the net flux of the uniform electric field of Exercise 1.15 through a cube of side 20 cm oriented so that its faces are parallel to the coordinate planes?

(a) Two insulated charged copper spheres A and B have their centers separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is \(6.5 × 10^{−7} C\)? The radii of A and B are negligible compared to the distance of separation. 
(b) What is the force of repulsion if each sphere is charged double the above amount, and the distance between them is halved?

A polythene piece rubbed with wool is found to have a negative charge of \(3 × 10^{−7} C\). 
(a) Estimate the number of electrons transferred (from which to which?) 
(b) Is there a transfer of mass from wool to polythene?

A charged particle oscillates about its mean equilibrium position with a frequency of $10^9\, Hz$. The frequency of electromagnetic waves produced by the oscillator is

A radio can tune to any station in $7.5\, MHz$ to $12\, MHz$ band. The corresponding wavelength band is

A plane electromagnetic wave travels in vacuum along z-direction. If the frequency of the wave is $40 \,MHz$ then its wavelength is

A short bar magnet has a magnetic moment of $0.48\, J\, T^{-1}$. The magnitude and direction of magnetic field produced by the magnet at a distance of $10 \,cm$ from the centre of the magnet on its axis is

A system has two charge s \(q_A = 2.5 × 10^{−7} C\) and \(q_B = −2.5 × 10^{−7 }C\) located at points A: (0, 0, − 15 cm) and B: (0, 0, + 15 cm), respectively. What are the total charge and electric dipole moment of the system?

Two point charges \(q_A = 3µC\) and \(q_B = −3µC\) are located 20 cm apart in vacuum. 
(a) What is the electric field at the midpoint O of the line AB joining the two charges? 
(b) If a negative test charge of magnitude \(1.5 × 10^{−9} C\) is placed at this point, what is the force experienced by the test charge?

When a glass rod is rubbed with a silk cloth, charges appear on both. A similar phenomenon is observed with many other pairs of bodies. Explain how this observation is consistent with the law of conservation of charge.

The electrostatic force on a small sphere of charge 0.4 µC due to another small sphere of charge − 0.8 µC in air is 0.2 N.
(a) What is the distance between the two spheres?
(b) What is the force on the second sphere due to the first?

Dimensional formula of Stefan's constant is

Electric flux at a point in an electric field is

A particle is moving along a straight line path according to the relation $s^2 = at^2 + 2bt + c$ s represents the distance travelled in t seconds and a, b, c are constants. Then the acceleration of the particle varies as.

A steel wire of length $l$ has a magnetic moment $M$. It is then bent into a semicircular arc. The new magnetic moment is

On an open ground, a motorist follows a track that turns to his left by an angle of $60^?$ after every $500\,m$. Starting from a given turn, the displacement of the motorist at the third turn is

The bulk modulus of a perfectly rigid body is :

When a metal wire elongates by hanging a load $Mg$ on it, the gravitational potential energy of mass $M$ decreases by $ Mgl $ . This energy appears

A short- circuited coil is placed in a time varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled (four times) and wire radius halved, the electrical power dissipated would be

If the eighth bright band due to light of wavelength $\lambda_1$coincides with ninth bright band from light of wavelength $\lambda_2$ , in Young's double slit experiment, then the possible wavelengths of visible light are

Two particles having position vectors $\vec{ r _{1}}=(3 \hat{ i }+5 \hat{ j }) m $ and $\vec{ r _{2}}=(-5 \hat{ i }-3 \hat{ j }) m $ are moving with velocities $\vec{ v _{1}}=(4 \hat{ i }+3 \hat{ j }) ms ^{-1}$ and $\vec{ v }_{2}=(a \hat{ i }+7 \hat{ j }) ms ^{-1}$. If they collide after $2\, s$, the value of $a$ is

Two short bar magnets of magnetic moments $m$ each are arranged at the opposite corners of a square of side d such that their centres coincide with the corners and their axes are parallel. If the like poles are in the same direction, the magnetic induction at any of the other corners of the square is

A square conducting loop of side length L carries a current I. The magnetic field at the centre of the loop is

Five cells each of emf $E$ and internal resistance $r$ send the same amount of current through an external resistance $R$ whether the cells are connected in parallel or in series. Then the ratio $\left( \frac{R}{r} \right)$ is