List of practice Questions

Electromagnetic waves were first of all produced in the laboratory by
The wavelength of electromagnetic waves produced by Hertz was about
A $100$ watt bulb emits monochromatic light of wavelength $400\,nm$. Calculate the number of photons emitted per second by the bulb.
The ratio of kinetic energy and the total energy of the electron in the $n^{th}$ quantum state of Bohr's atomic model of a hydrogen atom is
An electric charge in uniform motion produces
Electromagnetic waves are
Which among the following does not represent Maxwell's equation?
If $ \mu_{0}$ be the permeability and $\varepsilon_{0} $ be the permittivity of a medium, then its refractive index is given by
Hydrophs foetalis develops in case of defective alleles of two $\alpha$ -globin genes
Jacob's or criminal syndrome has a sex chromosome complement of
ZZ/ZW type of sex determination is seen in
In man which of the following genotypes and phenotypes may be the correct result of aneuploidy in sex chromosomes
The requirement of transmitting microwaves from one position to another on the earth is that
How many geo-synchronous satellites are required to provide the communication over the whole part of the earth
In sickle cell anaemia 6-valine of $\beta$-chain forms hydrophobic bonds creating helical polymer of $\cdots\cdots\cdots\cdots\cdots$ strands
In optical fibre communication system, light source can be
Filters are essential components to
Light emerging from the end of an optical fibre link must be detected and converted into electronic pulses for further processing so that
The height if geo-synchronous orbit from the surface of the earth is
Analog signal can be converted into digital signal and vice-versa with the help of a device called
A $10\, kW$ drilling machine is used to drill a bore in a small aluminium block of mass $8 \,kg$. Find the rise in temperature of the block in $2.5$ minutes, assuming $50\%$ power is used up in heating the machine itself or lost to the surroundings. (Specific heat of aluminium $= 0.91\, J \,g^{-1} \,^{\circ}C^{-1}$)
The $B-H$ curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with $1000 \, turns \, cm^{- 1}$ . The current that should be passed in the solenoid to demagnetise the ferromagnet completely is
The magnetic field at the point of intersection of diagonals of a square loop of side $L$ carrying a current $I$ is
Mixed $He^{+}$ and $O^{2 +}$ ions (mass of $H e^{+}=4 \, amu \, and \, that \, of \, O^{2 +}=16 \, amu$ ) beam passes a region of constant perpendicular magnetic field. If kinetic energy of all the ions is same, then
A $ 1\, kg $ block situated on a rough incline is connected to a spring of negligible mass having spring constant $ 100\, N\,m^{-1} $ as shown in the figure.
The block is released from rest with the spring in the unstretched position. The block moves $ 10\, cm $ down the incline before coming to rest. The coefficient of friction between the block and the incline is (Take $ g = 10\, ms^{-2} $ and assume that the pulley is frictionless)