Two concentric circular coils of 10 turns each are situated in the same plane. Their radii are 20 cm and 40 cm and they carry 0.2 A and 0.3 A currents respectively in opposite directions. The magnetic field at the center is:

Four equal charges \(Q\) are placed at the four corners of a square of side 'a'. Work done in removing a charge \(-Q\) from its centre to infinity is :

The ratio of energies of photons produced due to the transition of an electron of hydrogen atom from its
i. second permitted energy level to the first level and
ii. the highest permitted energy level to the first energy level is

The magnification (m) and focal length (f) of a plane mirror are:

The magnetic susceptibility of the material of a rod is 499. Permeability of vacuum is \( 4\pi \times 10^{-7} \text{ H/m} \). The absolute permeability of the material of the rod is:

The figure shows a long cylindrical straight wire of radius a carrying steady current (I). The current (I) is uniformly distributed across the cross-section of the wire. The ratio of the magnetic fields at points \(r=\frac{a}{3}\) and \(r=\frac{a}{2^{\prime}}\) respectively is: Here r is the distance of point from the axis of cylinder.

A capacitor charged from a 100 V d.c supply is found to have charge of 20 \(\mu\text{C}\). How much energy is stored in it ?

The speed of electromagnetic waves in a material medium is given by (symbols have their usual meanings):

The area (in sq. units) enclosed by the curve \(y=\frac{1}{2} x|x|\) and the line \(y=x\) is :

Read the passage carefully and give the answers to the question :
India was amongst the first countries in the world to initiate action plans and programmes at a national level to attain total reproductive health as a social goal.
These programmes called 'family planning' were initiated in 1951 and were periodically assessed over the past decades. Improved programmes covering wider reproduction-related areas are currently in operation. Creating awareness among the people about various reproduction-related aspects and providing facilities and support for building up a reproductively healthy society are the major tasks under these programmes.
'Saheli' - an oral contraceptive pill, also known as the 'Once a week' pill, was developed by :

A carrier wave of peak voltage 24 V is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of 70% ?

A coin is tossed and a die is thrown. The probability that the outcome will be a tail on the coin or a number greater than 3 on the die is

If the length of a wire is doubled while keeping its material and cross-sectional area same, the resistance of the wire