Electric Charges and Fields — Physics STD 12 Science — Question

An object is placed 40 cm  from a concave mirror of focal length 20 cm  The image formed is(a) Real, inverted and same in size(b) Real, inverted and smaller(c) Virtual, erect and larger(d) Virtual, erect and smaller

The drift current in a p-n junction is from the:

The device is based on the principle of mutual induction is:

Which of the following is not true for electromagnetic waves?

A circular disc of which 2/3 part is coated with yellow and 1/3 part is with blue. It is rotated about its central axis with high velocity, then it will be seen as(a) Green   (b) Brown(c) White                                            (d) Violet

Unit of magnetic field is :

Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below. Assertion (A): Magnetic field is useful in producing parallel beam of charged particle. Reason (R): Magnetic field inhibits the motion of charged particle moving across it.

The power of a person's spectacle lenses is +2 D . He is suffering from which of the following defects?

A uniform sphere is placed on a smooth horizontal surface and a horizontal force F is applied on it at a distance h above the surface. The acceleration of the centre:

1. Is maximum when h = 0.
2. Is maximum when h = R.
3. Is maximum when h = 2R.
4. Is independent of h.