A person cannot see the objects distinctly, when placed at a distance less than 50 cm.(a) Identify the defect of vision.(b) Give two reasons for this defect.(c) Calculate the power and nature of the lens he should be using to see clearly the object placed at a distance of 25 cm from his eyes.(d) Draw

Q 1 { ques: “The spontaneous emissions of radiations from heavy nucleus (A > 83) is called:”, ans: “Radioactivity”, ansSel: [ “Nuclear fission”, “Nuclear Fusion”, “None” ] }, // Q 2 { ques: “Alpha particles are:”, ans: “helium nuclei”, ansSel: [ “Protons”, “negatively charged”, “Positrons” ] }, // Q 3 { ques: “When a nucleus


1.  Which of the following does not change in a transformer ? (a)  Current (b) Voltage (c) Frequency (d) All of the above Ans: c 2.  In a transformer the energy is conveyed from primary to secondary (a) through cooling coil (b) through air (c) by the flux (d) none of the above Ans: c

DC Generators

1. Laminations of core are generally made of (a)     case iron (b)     carbon (c) silicon steel (d) stainless steel Ans: c 2. Which of the following could be lamina-proximately the thickness of laminations of a D.C. machine ? (a) 0.005 mm (b) 0.05 mm (c) 0.5 m (d) 5 m Ans:

Alternating Current

1. A sine wave has a frequency of 50 Hz. Its angular frequency is _______ radian/second. (a) 100 n (b) 50 jt (c) 25 JT (d) 5 n Ans: a 2. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance


1. The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as (a)     self-inductance (b)     mutual inductance (c) series aiding inductance (d) capacitance Ans: a 2. As per Faraday’s laws of electromagnetic induction, an e.m.f. is induced in a


1. Tesla is a unit of (a) field strength (b) inductance (c) flux density (d) flux Ans: c 2. A permeable substance is one (a)     which is a good conductor (6)     which is a bad conductor (c) which is a strong magnet (d) through which the magnetic lines of force can

Current Electricity

1. The S.I. unit of power is (a) Henry (b) coulomb (c) watt (d) watt-hour Ans: c 2. Electric pressure is also called (a) resistance (b) power (c) voltage (d) energy Ans: c 3. The substances which have a large number of free electrons and offer a low resistance are called (a)     insulators


1. The force between two charges is 120 N. If the distance between the charges is doubled, the force will be (a) 60 N (b) 30 N (c) 40 N (d) 15 N Ans: b 2. The electric field intensity at a point situated 4 meters from a point charge is 200 N/C. If the