Pair-production means :

Which of the following is an incorrect statement?

The longest wavelength in Balmer Series of hydrogen spectrum will be:

The electric field vector \( \vec{E} \) and magnetic field vector \( \vec{B} \) in electromagnetic waves are :

A storage battery of emf 8.0 V and internal resistance 0.5 \(\Omega\) is being charged by a 60 V dc supply using a series resistor of 12.5 \(\Omega\). The terminal potential difference between the terminals of the battery during charging is

The radius of a wire having resistance R is made half and its length reduced to one - fourth of its original length. The new resistance of the wire will be

The reactance of a circuit is zero. It is possible that the circuit contains:
A. an inductor and a capacitor
B. an inductor but no capacitor
C. a capacitor but no inductor
D. Neither inductor nor capacitor
Choose the correct answer from the options given below:

A proton is accelerated by a potential V and the de-Broglie wavelength associated with it is \(\lambda\). By how much potential a deuteron should be accelerated to acquire the same de-Broglie wavelength as that of a proton?

If the function
\(f(x)=\left\{\begin{array}{ll}a x+2, & x \leq 1 \\x^2+3 x+b, & x>1\end{array}\right.\)
is differentiable at \(x=1\), then the value of \((2 a+b)\) is

Choose the correct statements from the following.
A. Like light waves, thermal radiations are also electromagnetic radiation.
B. Electromagnetic waves can travel in vacuum but mechanical waves cannot do so.
C. Gamma rays are more energetic than X-rays.
D. Microwaves are heat waves so they always produce heating.
E. Displacement current is a fictious current and has nothing in common with conduction current.
Choose the correct answer from the options given below:

Match List - I with List - II

List - I	List - II
(A) Corner point of a feasible region	(I) The line segment joining any two arbitrary points of the region always lies entirely within the region
(B) Bounded feasible region	(II) can not be enclosed within a circle
(C) Unbounded feasible region	(III) can be enclosed within a circle
(D) Convex region	(IV) is a point of intersection of two boundary lines in the feasible region

Choose the correct answer from the options given below:

Six identical cells, each of emf 3 V and internal resistance of r, are connected in series to a \( 3 \text{ } \Omega \) resistance. If the net current flowing in the circuit is 2.0 A. The internal resistance of the cell is

Read the passage carefully and answer the given questions.
DNA Fingerprinting
Polymorphism in DNA sequence is the basis of genetic mapping of the human genome as well as of DNA fingerprinting. DNA fingerprinting involves identification of differences in some specific regions in the DNA sequence called repetitive DNA. It works on the principle of polymorphisms in DNA sequences. The repetitive DNA are separated from bulk genomic DNA. The bulk DNA forms a major peak and the other small peaks are referred to as satellite DNA. These repetitive/satellite DNA sequences show a high degree of polymorphisms and form the basis of DNA fingerprinting.
Which one of the following techniques is involved in DNA fingerprinting?