ASSERTION : In the absence of an externally applied electric field, the displacement per unit volume of a polar dielectric material is constant. REASON : In polar dielectrics, each molecule has a temporary dipole moment but these are randomly oriented in the absence of an externally applied electric field.
Correct!
Wrong!
ASSERTION : Two bulbs of same wattage, one having a carbon filament and the other having a metallic filament are connected in series. Metallic bulbs will glow more brightly than carbon filament bulb. REASON : Carbon is a semiconductor.
Correct!
Wrong!
ASSERTION : Magnetic field is useful in producing parallel beam of charged particle. REASON : Magnetic field inhibits the motion of charged particle moving across it.
Correct!
Wrong!
ASSERTION : The magnetic poles of earth do not coincide with the geographic poles. REASON : The discrepancy between the orientation of a compass and true north-south direction is known as magnetic declination.
Correct!
Wrong!
ASSERTION : A copper sheet is placed in a magnetic field. If we pull it out of the field or push it into the field, we experience an opposing force. REASON : According to Lenz’s law eddy current produced in sheet opposes the motion of the sheet.
Correct!
Wrong!
ASSERTION : An electric heater is heated first by direct and then by alternating currents. For both the currents, the potential difference across the ends of the heater is the same. The rate of production of heat will be different in two cases. REASON : The resistance of a coil in alternating current will be more than the resistance of a coil in direct current, hence heat produced in case of direct current will be low.
Correct!
Wrong!
ASSERTION : If a plane glass slab is placed on the letters of different colours all the letters appear to be raised up to the same height. REASON : Different colours have same wave lengths.
Correct!
Wrong!
ASSERTION : When tiny circular obstacle is placed in the path of light from some distance, a bright spot is seen at the centre of the shadow of the obstacle. REASON : Destructive interference occurs at the centre of the shadow.
Correct!
Wrong!
ASSERTION : The relative velocity of two photons travelling in opposite direction is the velocity of light. REASON : The rest mass of a photon is zero.
Correct!
Wrong!
ASSERTION : There is a difference in the spectrum of sunlight passing yellow glass and that of the light from a sodium vapour lamp. REASON : The sunlight always gives continuous spectrum with absorption lines (the Fraunhofer lines).
Correct!
Wrong!
