An electric kettle has two heating elements. One brings it to boil in ten minutes and the other in fifteen minutes. If two heating filaments are connected in parallel, the water in kettle will boil […]
A disc of radius 0.1 m is rotating with a frequency 10 rev/sec in a normal magnetic field of strength 0.1 tesla. Net induced emf is
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(a) 2 π x 10⁻² V (b) […]
Two bulbs 40 watt and 60 watt and rated voltage 240 V are connected in series across a potential difference of 420 V. Which bulb will work at above its rated voltage
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A galvanometer is converted into an ammeter by connecting
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(a) low resistance in parallel (b) low resistance in series (c) high resistance in series (d) high resistance in parallel
Correct Answer:
low resistance […]
A long straight wire carries a certain current and produces a magnetic field of 2 x 10⁻⁴ weber/m² at a perpendicular distance of 5 cm from the wire. An electron situated at 5 cm from […]
An electron moving in a uniform magnetic field of induction of intensity B, has its radius directly proportional to
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(a) its charge (b) magnetic field (c) speed (d) none of these
Correct […]
A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in uniform magnetic field. What should be the energy of an α-particle to describe a circle of same radius […]
Curie temperature above which
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(a) paramagnetic material becomes ferromagnetic material (b) ferromagnetic material becomes diamagnetic material (c) Ferromagnetic material becomes paramagnetic material (d) paramagnetic material becomes diamagnetic material
Correct Answer:
Ferromagnetic material becomes […]
An alternating electric field, of frequency v, is applied across the dees (radius = R) of a cyclotron that is being used to accelerate protons (mass = m). The operating magnetic field (B) used in […]
The direction of magnetic line of force of a bar magnet is
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(a) from south to north pole (b) from north to south pole (c) across the bar magnet (d) from south […]
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