In a half wave rectifier, the frequency of the output is :

A uniform electric field of 20 V m -1 exists in the vertically downward direction. What will be the increase in the electric potential as one goes up through a height of 60 cm?

The ratio of velocity of light in vacuum to that of velocity of light in medium is: (where symbols have their usual meanings).

When a potential difference is applied across the ends of a conductor, the electric field exists :

Two concentric coils \(X\) and \(Y\), each of radius \(2 \pi cm\), are placed at right angles to each other. If \(X\) and \(Y\) carry 4 A and 3 A currents, respectively, then the value of the magnetic field (in \(Wb m ^{-2}\) ) at the centre of the coils is (Take \(\mu_0=4 \pi \times 10^{-7} Wb A ^{-1} m^{-1}\) )

Read the following statements carefully and identify the correct statements.
(A) Most interference and diffraction effects exist even for longitudinal waves like sound in air
(B) Optical fibers work on the phenomenon of total internal reflection
(C) Optical density and mass density are the same
(D) Polarisation phenomena are specific to transverse waves like light waves
Choose the correct answer from the options given below:

Rohit has been given two converging lenses of focal lengths 1.25 cm and 5 cm, respectively to design a compound microscope. If it is desired to have a magnification of 30, what would be the separation between the objective and the eyepiece when the final image is formed at the least distance of distinct vision?

Match List-I with List-II

List-I (Structures)	List-II (Characteristics)
(A) Heterochromatin	(I) A set of positively charged basic proteins
(B) Nucleosomes	(II) Densely packed and inactive genetic material
(C) Histones	(III) Transcriptionally active genetic material
(D) Euchromatin	(IV) DNA is wrapped around the histone octamer to formthis structure

Choose the correct answer from the options given below:

What is the relative permittivity of a medium of relative permeability \( \mu_r = 1.0 \) in which an electromagnetic wave travels at a speed of \( v = 2 \times 10^8 \, \text{m s}^{-1} \)?

Which of the following statements are true?
(A) Rheostat can be used both as a variable resistance and a potential divider.
(B) An electrical circuit is functional only if all the components of the circuit are connected in proper order, assuming that all circuit components/ devices are in working condition and key is closed.
(C) An open circuit means a break in some part of a circuit which could be deliberate such as a key in open position or a fault such as broken wire or burnt out component(s) or loose connection.
(D) Rheostat as a potential divider gives variable resistance.
Choose the correct answer from the options given below:

A radioactive material with half life of 6.25 years undergoes beta decay. How much fraction of material is decayed after 25 years:

In the depletion region of a diode :
(A) There are no mobile charges
(B) Equal number of holes and electrons exist, making the region neutral
(C) recombination of holes and electrons has taken place
(D) Immobile charged ions exist
(E) There are mobile charges
Choose the correct answer from the options given below :

If a man with blood group A marries a woman with blood group AB. Which of the following blood group will never be found in their children?