(i) Two bulbs of power ratings 100 W and 40 W, designed to operate on the same voltage, are connected in parallel to a battery source as shown in Figure 1 below. Currents flowing across points 1,2 and 3 are I1, I2 and I3 respectively.
A circular coil having N turns of radius R carries a current I and produces a magnetic field T at its centre O. If this coil is opened and rewound such that the radius of the newly formed coil is 2R, and the same current I passed through it, the magnetic field at the centre O will be:
(a) 2T (b) T (c) T/2 (d) T/4
(iii) Assertion: Magnetic lines of force do not intersect each other.
Reason: At the point of intersection, the magnetic field will have two directions.
(a) Both Assertion and Reason are correct, and Reason is the correct explanation for Assertion. (b) Both Assertion and Reason are correct, but Reason is not the correct explanation for Assertion. (c) Assertion is true and Reason is false. (d) Assertion is false and Reason is true.
(iv) The focal length of a double convex lens is equal to the radius of curvature of either surface. The refractive index of its material is:
(a) 3/2 (b) 1 (c) 4/3 (d) Zero
(v) Which one of the following statements is correct in case of Fraunhofer’s single slit diffraction experiment?
(a) All bright fringes are of same intensity. (b) Central bright fringe is the brightest. (c) Central fringe is a dark fringe. (d) Angular width of central fringe increases with an increase in wavelength of the incident monochromatic light.
(vi) The de Broglie wavelength of a moving particle varies:
(a) directly with its velocity. (b) directly with its momentum. (c) directly with its kinetic energy. (d) inversely with its linear momentum.
(vii) Which one of the following statements is correct with reference to Semiconductor Physics?
(a) N type semiconductor has a majority of holes. (b) To convert a pure semiconductor into a P type semiconductor, Phosphorous is used as a dopant. (c) In energy band diagram of a metal, forbidden band is absent. (d) Resistance of a semiconductor increases on increasing its temperature.
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