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The resistance of a coil for D.C. is in ohms. In A.C., the resistance
An X - ray tube is operated at a constant potential difference and it is required to get X - ray of wavelength not less then 0. 2 nano-metres. Then the potential difference in kilo-volts is [ h = 6.63 x 10-34 J − sec ; e = 1.6 x 10-19 C ; c = 3x 108 m s-1 ]
A photon of energy 2. 5eV and wavelength λ falls on a metal surface and the ejected electrons have a velocity 'V' . If the wave length λ of incident light is decreased by 20%, the velocity of emitted electrons is doubled, then the work function of the metal is
A 2μ F capacitor is charged to 100 volt and then its plates are connected by a conducting wire. The heat produced is
A 4 V battery of internal resistance 1 Ω sends a current through a 3 Ω resistor. The terminal potential difference is
The maximum current that flows through a fuse wire before it blows out varies with its radius r as
Consider telecommunication through optical fibres. Which of the following statements is not correct
When a proton is accelerated with 1 volt potential difference, then its kinetic energy is
A conductor rod of length L rotates with angular speed ω in a uniform magnetic field of induction B which is perpendicular to its motion. The induced e.m.f developed between the two ends of the rod is
The induced e.m.f. produced in the primary and secondary coils is 2 mV and 5 mV respectively. If the rate of change of current is 20 A-s-1, then coefficient of mutual induction of the secondary coil is
Which of the following rays are not electromagnetic wave?
A sphere S1 of radius r1 encloses a total charge Q. If there is another concentric sphere S1 of radius r2 > r1 and there be no additional charges between S1 and S2, the ratio of electric flux through S1 and S2 is
An electron of charge e coulomb passes through a potential difference of V volt. Its energy in joule will be
An electric dipole consists of two opposite charges of magnitude +- q seperated by 2a. When the dipole is placed in uniform electric field E, to have minimum potential energy, then dipole moment p makes which the following angle with E
The capacitance of a parallel plate capacitor is 10 μF when distance between its plates is 8 cm. If distance between the plates is reduced to 4 cm, its capacitance will be
The difference between the mass of a nucleus and the total mass of the constituents is its
A body of mass 1g and carrying a charge 10-8 C passes from two points P and Q. P and Q are at electric potentials 600V and 0V respectively. The velocity of the body at Q is 20 cm s-1 . Its velocity in ms-1 at P is
A heavy nucleus at rest breaks into two fragments which fly off with velocities 8:1. The ratio of radii of the fragments is
When the photons of energy hv fall on a photo-sensitive surface (work function hv₀) electrons are emitted from the metallic surface. This is known as photoelectric effect. The electron coming out of the surface have a kinetic energy. Then it is possible to state that
The magnifying power of a simple microscope M is given by
A prism is made up of material of refractive index √ 3 . The angle of the prism is A. If the angle of minimum deviation is equal to the angle of the prism, then the value of A is
The region near the junction of p - n diode where there are no charge carriers is called
Three semi-conductors are arranged in the increasing order of their energy gap as follows. The correct arrangement is
When distance between source of light and observer decreases, then the apparent frequency of light
Laser light is considered to be coherent as it consists of
When two coherent monochromatic light beams of intensities I and 4I are superimposed, the ratio between maximum and minimum intensities in the resultant beam is
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