An electric motor operates at 20 r.p.s. What will be the approximate power delivered by the motor, if it supplies a torque of 75 N-m?
Light of wave length λ and photon energy 2eV falling on a metal surface produces photoelectrons of maximum velocity V. If the λ is decreased by 25% and the maximum velocity of electron is doubled, the work function of the metal is (in eV)
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In an ideal parallel LC circuit, the capacitor is charged by connecting it to a.c.d. source, which is then disconnected. The current in the circuit
When a resistance of 2 Ω is connected across the terminals of a cell, the current is 0.5 amperes. When the resistance is increased to 5 ohm, the current is 0.25 amperes. The internal resistance of the cell is
A particle is moving on a circular path with constant speed, then its acceleration will be
A capacitor is having a capacity of 2 pF. Electric field across the capacitor is changing with a value of 1012 V/s. The displacement current is
A 10 m long wire of 20Ω resistance is connected in series with a battery of 3 volt e.m.f. (negligible internal resistance) and a 10Ω resistance. The Potential gradient of wire in volt per meter is
If the current is halved in a coil, then the energy stored is how much times the previous value
Three capacitors each of capacitance C and of breakdown voltage V are joined in series. The capacitance and breakdown voltage of the combination will be:
The capacitance of an isolated spherical conductor of radius 15 cm is
If 1000 droplets each of charge q and radius r are mixed to form a big drop, then the potential of big drop, as compared to small droplet will be
A block of weight 200N is pulled along a rough inclined plane of inclination 45o with the horizontal. If the coefficient of friction is 0.5, the retardation is
A man inside an artificial satellite feels weightlessness because the force of attraction due to earth is
Relation between the colour and the temperature of a star is given by
If the radius of earth's orbit is made 1/4, the duration of an year will become
Mean kinetic energy per degree of freedom of gas molecules is
In the Young's double slit experiment, the central bright fringe can be identified
A wire is wound in the form of a solenoid of length and diameter d. When a strong current is passed through the solenoid there is tendency to
Two concentric circular coils of ten turns each are situated in the same plane. Their radii are 20 cm and 40 cm and they carry respectively 0.2 A and 0.3 A currents in opposite direction. The magnetic field in tesla at the centre is
The magnetic field at the centre of current I carrying loop of radius r, is
To shield an instrument from external magnetic field, it is placed inside a cabin made of
The field of a short bar magnet at a distance of 1 m on its axial line is 1 oersted. At a distance of 2 m on the same line, the intensity in oersted will be
Bernoulli's theorem is based on the law of conservation of
A magnet of magnetic moment M is cut into two equal parts. The two parts are placed perpendicular to each other so that their north poles touch each other. The resultant magnetic moment is
The excess pressure inside one soap bubble is three times that of a second bubble. The ratio of the volumes of the first bubble to that of second bubble is
The moment of inertia of a meter scale of mass 0.6 kg about an axis perpendicular to the scale and located at the 20 cm position on the scale in kg m2 is (Breadth of the scale is negligible)
A metallic wire is suspended by attaching some weight to it. If α is the longitudinal strain and Y is Young's modulus, then the ratio between elastic potential energy and the energy density is equal to
A force of 100 dynes acts on mass of 5 gm for 10 sec. The velocity produced is
A body falling for seconds covers a distance S equal to that covered in next second. Taking g=10m/s2,S=
4 videos|8 docs|51 tests
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4 videos|8 docs|51 tests
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