Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Physics

Can a galvanometer as such be used for measuring the current? Explain.

Derive the expression for the electric potential due to an electric dipole at a point on its axial line.

Depict the equipotential surfaces due to an electric dipole. 

(i)Obtain the expression for the torque `vecτ` experienced by an electric dipole of dipole moment `vecP` in a uniform electric field, `vecE` .

(ii) What will happen if the field were not uniform?

1. Define torque acting on a dipole of dipole moment \[\vec{p}\] placed in a uniform electric field \[\vec{E}\] Express it in the vector from and point out the direction along which it acts. Express it in the vector from and point out the direction along which it acts.
2. What happens if the field is non-uniform?
3. What would happen if the external field
   \[\vec{E}\]  is increasing (i) parallel to \[\vec{p}\] and (ii) anti-parallel to \[\vec{p}\]?

With the help of a neat and labelled diagram, explain the principle and working of a moving coil galvanometer ?

Define current sensitivity of a galvanometer.

Write the expression for the torque \[\vec{\tau}\] acting on a dipole of dipole moment  \[\vec{p}\] placed in an electric field \[\vec{E}\].

Why does a galvanometer when connected in series with a capacitor show a momentary deflection, when it is being charged or discharged?

How does this observation lead to modifying the Ampere's circuital law?

Hence write the generalised expression of Ampere's law.

Answer the following question :
Define 'bandwidth' and describe briefly its importance in communicating signals ?

Find the resultant electric field due to an electric dipole of dipole moment, 2aq, (2a being the separation between the charges ±± q) at a point distant 'x' on its equator.

An electric dipole of length 2 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of \[8\sqrt{3}\] Nm. Calculate the potential energy of the dipole, if it has a charge \[\pm\] 4 nC.

An electric dipole of length 1 cm, which placed with its axis making an angle of 60° with uniform electric field, experience a torque of \[6\sqrt{3} Nm\] . Calculate the potential energy of the dipole if it has charge ±2 nC.

Block diagram of a receiver is shown in the figure:

(a) Identify ‘X’ and ‘Y’.

(b) Write their functions.

Define the current sensitivity of a galvanometer ?

Write current sensitivity of a galvanomete S.I. unit. 

Figure shows two circuits each having a galvanometer and a battery of 3V.

When the galvanometers in each arrangement do not show any deflection, obtain the ratio R₁/R₂.

Define electric dipole moment. Is it a scalar or a vector? Derive the expression for the electric field of a dipole at a point on the equatorial plane of the dipole.

Distinguish between ‘Analog and Digital signals’.