Electric field due to an electric dipole is

The current sensitivity of a moving coil galvanometer increases by 35%, when its resistance is increased by a factor 3. The voltage sensitivity of galvanometer changes by a factor

What is the relation between electric intensity and electric flux?

Plot a graph showing the variation of resistance of a conducting wire as a function of its radius. Keeping the length of the wire and its temperature as constant.

What is magnetic susceptibility of super conductors.

Two point charges q₁ and q₂ are located at r₁and r₂ respectively in an external electric field E. Obtain the expression for the total work done in assembling this configuration.

In a meter bridge, two unknown resistances R and S when connected in two gaps, give a null point at 40 cm from one end. What is the ratio R and S?

A circular coil fo N turns and radius R carries a current I. It is unwound and rewound to make another coil of radius R/2, current I remaining the same. Calculate the ratio of the magnetic moments of the new coil and the original coil.

Two capacitors of 25\(\mu F \ and \ 100\mu F\) are connected in series to a source of 120 V. Keeping their charges unchanged, they are separated and connected in parallel to each other. Find out 
(i) pot.diff. between the plates of each capacitor
(ii) energy loss in the process.

In a meter bridge, the null point is found at a distance of 33.7 cm from A. If a resistance of 12\(\Omega \) is connected in parallel with S, the null point occurs at 51.9 cm. Determine the values of R and S.

A circular coil of 200 turns and radius 10 cm is placed in a uniform magnetic field of 0.5 T, normal to the plane of the coil.  If the current in the coil is 3.0 A, calculate the

(a) total torque on the coil.

(b) total force on the coil.

(c) average force on each electron in the coil, due to the magnetic field.

Assume the area of cross-section of the wire to be 10^-5m² and the free electron density is 10²⁹/m³.

Derive the expression for the energy stored in a parallel plate capacitance C with air as medium between its plates having charges Q and -Q.Show that this energy can be expressed in terms of electric field as \(\frac { 1 }{ 2 } { \varepsilon }_{ 0 }E^{ 2 }Ad\) where A is the area of each plate and d is the energy separation between the plates.How will the energy stored in a fully charged capacitor change when the separation between the plates is doubled and a dielectric medium of dielectric constant 4 is introduced between the plates?

Explain how the cells are grouped in parallel. Obtain the condition for maximum current through an external resistor.

What is a cyclotron ? Discuss its construction, working and theory. Explain cyclotron frequency.

A point charge \(+10\mu \) is at a distance 5cm directly above the centre of square of side 10cm as shown in fig.What is the magnitude of the electric flux through the square?

A parallel plate capacitor contains a mica sheet of thickness \(d_1=10^{-3}m\) and one fibre sheet of thickness \(d_2=0.5\times 10^{-3}m.\) Values of K for mica and fibre are 8 and 2.5 respectively. Fibre breaks down in electric field of \(6.4\times 10^6Vm^{-1}\). What maximum voltage can be applied to the capacitor?

A potentiometer wire of length 1m is connected to a driver cell of em 3V as shown in the figure. When a cell of 1.5V emf is used in the secondary circuit the balance point is found to be 60 cm. On replacing this cell and using a cell of unknown emf, the balancing point shifts to 80cm

(i)Calculate unknown emf of the cell.

(ii)Explain with reason whether the circuit works if the driver cell is replaced with a cell of emf 1V

(iii)Does the high resistance R, used in the secondary circuit affect the balance point? Justify your answer.

(a)  Show that a planar loop carrying a current I, having N closely wound turns and area of cross-section A, possesses a magnetic moment \(^{\rightarrow}_{m}\) = NI \(^{\rightarrow}_{A}\).

(b)  When this loop is placed in a magnetic field \(^{\rightarrow}_{B}\), find out the expression for the torque acting on it.

(c) A galvanometer coil of 50 \(\Omega\) resistance shows full scale deflection for a current of 5mA.  How will you convert this galvanometer into a voltmeter of range 0 to 15V?