The radius of a nucleus varies with its mass number A as:

Two light beams of intensities in the ratio 25:9 are allowed to interfere. The ratio of the intensities of maxima and minima will be

The radius of innermost electron orbit of a hydrogen atom is \( 5.3 \times 10^{-11} \text{ m} \). What is the radius of n = 2 orbit ?

Four point charges -2Q, +q, -2q and +Q are placed at four corners of a square A, B, C and D, respectively, as shown in the figure and OA = OB = \( a/\sqrt{2} \). If the potential at the center of a square is zero, what is the relation between Q and q?

Which of the following statements are correct?
A. Electrical resistivity of copper is low.
B. Temperature coefficient of resistance for semiconductors is positive.
C. On carbon resistors, colour of the second strip indicates the multiplier.
D. During charging of a cell, the terminal potential difference becomes greater than the emf of the cell.
E. The cells are connected in series to get more voltage, than cells connected in parallel.
Choose the correct answer from the options given below:

An electric dipole of length 2 cm is placed at an angle of \(30^\circ\) with an electric field \(3 \times 10^5 \text{ N C}^{-1}\). If the dipole experiences a torque of \(9 \times 10^{-3} \text{ N m}\), the magnitude of either charge of the dipole is

A long wire is bent into a circular coil of one turn and then into a circular coil of smaller radius having n turns. If the same current passes in both the cases, then the ratio of the magnetic fields produced at the centers in two cases will be :

Area of a rectangle having vertices \(P, Q, R\) and \(S\) with position vectors \(-\hat{i}+\frac{1}{2} \hat{j}+4 \hat{k}, \hat{i}+\frac{1}{2} \hat{j}+4 \hat{k}, \hat{i}-\frac{1}{2} \hat{j}+4 \hat{k}\) and \(-\hat{i}-\frac{1}{2} \hat{j}+4 \hat{k}\) respectively is :

A step-up transformer operates on a 220 V line and supplies a current of 2 A. The ratio of primary and secondary winding is 1 : 25. Assuming 100% efficiency, the output power of the transformer is:

Read the following paragraph and answer the given questions.
Repeated amplification is achieved by the use of a thermostable DNA polymerase (isolated from a bacterium, Thermusaquaticus}), which remain active during the high temperature induced denaturation of double stranded DNA. The separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation. The separated bands of DNA are cut out from the agarose gel and extracted from the gel piece. The convention for naming these enzymes is the first letter of the name comes from the genus and the second two letters come from the species of the prokaryotic cell from which they were isolated, e.g., EcoRI comes from Escherichiacoli} RY 13. In EcoRI, the letter 'R' is derived from the name of strain. Roman numbers following the names indicate the order in which the enzymes were isolated from that strain of bacteria. Stanley Cohen and Herbert Boyer accomplished this in 1972 by isolating the antibiotic resistance gene by cutting out a piece of DNA from a plasmid which was responsible for conferring antibiotic resistance. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA, RNA, protein, polysaccharides etc. The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol.

In the isolation process of genetic material, the purified DNA can be precipitated out after the addition of:

Solution of \(\frac{dy}{dx} = 2^{y-x}\) is:

If \(A=\left[\begin{array}{cc}-2 & 3 \\ k & 4\end{array}\right]\) is a singular matrix then value of \(k\) is :

How many moles of dichromate ion will be required to oxidize one mole of \(Fe^{2+}\) to \(Fe^{3+}\) ions in acidic solution?