Two positive point charges of \(q_1=0.2 \mu C\) and \(q_2=0.01 \mu C\) are placed \(r_i=10 cm\) apart. The work done in reducing the distance to \(r_f=5 cm\) will be

What will be the ratio of radii of two nuclei having their mass numbers in the ratio of 64:125?

A mark placed on the surface of a sphere is viewed through glass from a position directly opposite. If the diameter of the sphere is 10 cm and refractive index of glass is 1.5, the image would be at

Two circular coils of diameter 10 cm and 20 cm, carrying equal currents have the same number of turns. The ratio of magnetic fields produced at the center of coils, respectively will be

An AC (220 V, 50 Hz) circuit has a resistance of 3 \(\Omega\) and an impedance of 5 \(\Omega\) . The power factor of the circuit will be :

If the total energy is transferred by the electromagnetic waves on a surface be \(U\) in time \(t\), then the total momentum delivered to the surface is

dentify the correct statements.
(A) Photographic plates are sensitive to infrared waves.
(B) Infra-red waves are invisible but can cast shadows like visible light.
(C) Photographic plates are sensitive to ultraviolet rays.
(D) Infrared photons have more energy than photons of visible light.
Choose the correct answer from the options given below:

Read the passage carefully and answer the questions
Many halogen containing organic compounds are present in nature and some of them are clinically useful. These classes of organic compounds find a wide range of applications in our daily life as well as in industries. Many of the polyhalogen compounds are useful too in agriculture. However, some of these compounds cannot be easily decomposed and are thus considered to be environmental hazards. These halo compounds are prepared via different synthetic routes where a variety of organic compounds can be used as substrates such as amines, hydrocarbons etc. They are used as solvents for relatively non-polar compounds. These compounds exhibit substitution and elimination reactions, in addition to their reactions with different metals, which leads to the formation of a versatile starting material for others organic compounds.
The reaction of aryl halide with sodium and dry ether is known as

The self-inductance of an inductance coil having 100 turns is 20 mH. The total flux through the coil for a current of 40 mA is :

The inverse of the matrix \(\left[\begin{array}{cc}2 & -1 \\ 1 & 0\end{array}\right]\) is:

For any two matrices A and \(B , AB + BA\) is a possible matrix, then :

During the process of spermatogenesis, the secondary spermatocytes
undergo ___________ division to produce ___________ spermatids

Let \(f(x)=\left\{\begin{array}{ll}\frac{|x|}{x}, & x \neq 0 \\ 1, & x=0\end{array}\right.\), and \(g(x)=\left\{\begin{array}{ll}x \sin \frac{1}{x}, & x \neq 0 \\ 0, & x=0\end{array}\right.\). Then at the origin, which one is true?