Science (English Medium) कक्षा १२ - CBSE Important Questions

First Deaflympic Games was organized in the year ______.

Match the following:

Choose the correct option from the following:

Make a table of test items listed under fitness test by SAI (Age group 9-18 yrs).

Explain the procedure and scoring of 50 MTS Run.

Explain the procedure and scoring of partial curl-up.

Elucidate any six effects of exercise on muscular system.

Which of the following is NOT the factor affecting projectile trajectory?

The ability to tolerate higher concentrations of ______ can help in improving endurance performance.

Explain any two methods to develop flexibility.

How does the electric flux due to a point charge enclosed by a spherical Gaussian surface get affected when its radius is increased?

(a) Derive an expression for the electric field E due to a dipole of length '2a' at a point distant r from the centre of the dipole on the axial line.
(b) Draw a graph of E versus r for r >> a.
(c) If this dipole were kept in a uniform external electric field E₀, diagrammatically represent the position of the dipole in stable and unstable equilibrium and write the expressions for the torque acting on the dipole in both the cases.

An infinitely large thin plane sheet has a uniform surface charge density +σ. Obtain the expression for the amount of work done in bringing a point charge q from infinity to a point, distant r, in front of the charged plane sheet. 

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 \[\vec{p}\]?

A point charge (+Q) is kept in the vicinity of an uncharged conducting plate. Sketch the electric field lines between the charge and the plate?

A hollow cylindrical box of length 1 m and area of cross-section 25 cm² is placed in a three dimensional coordinate system as shown in the figure. The electric field in the region is given by `vecE = 50xhati` where E is NC­⁻¹ and x is in metres. Find

(i) Net flux through the cylinder.

(ii) Charge enclosed by the cylinder.

A charge ‘q’ is placed at the centre of a cube of side l. What is the electric flux passing through each face of the cube?

Define dipole moment of an electric dipole. Is it a scalar or a vector?

An electric dipole of dipole moment `vecP` is placed in a uniform electric field `vecE` with its axis inclined to the field. Write an expression for the torque `vecT` experienced by the dipole in vector form. Show diagrammatically how the dipole should be kept in the electric field so that the torque acting on it is:

1. maximum
2. Zero

Answer the following question.
Derive an expression for the electric field at any point on the equatorial line of an electric dipole. 

The electric flux through a closed Gaussian surface depends upon ______.