Practice Questions

Q29.A radar has a power of 1 Kw and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500 m. The maximum distance upto which it can detect object located on the surface of the earth (Radius of earth = 6.4 × 106 m ) is (1) 80 km (2) 16 km (3) 40 km (4) 64 km

Q53.In a common base mode of a transistor, t collector current is 5.488 mA for an emit current of 5.60 mA. The value of the base current amplification factor (β) will be (1) 48 (2) 49 (3) 50 (4) 51

Q57.How many moles of magnesium phosphate, Mg3(PO4)2 will contain 0.25 mole of oxygen atoms? (1) 0.02 (2) 3.125 × 10−2 (3) 1.25 × 10−2 (4) 2.5 × 10−2

Q59.According to Bohr's theory, the angular momentum of an electron in 5th orbit is (1) 25 πh (2) 1.0 πh (3) 10 πh (4) 2.5 πh

Q65.To get three images of a single object, one should have two plane mirrors at an angle of (1) 60∘ (2) 90∘ (3) 120∘ (4) 30∘

Q24.A cylinder of height 20 m is completely filled with water. The velocity of efflux of water (in ms−1 ) through a small hole on the side wall of the cylinder near its bottom is (1) 10 (2) 20 (3) 25.5 (4) 5