PHYSICS
Part I
Question 1
Choose the correct alternative (a), (b), (c) or (d) for each of the questions given below:
(i) Two point charges 17.7 μC and -17.7μC, separated by a very small distance, are kept inside a large hollow metallic sphere. Electric flux emanating through the sphere is:
(a) 2 ×106 Vm
(b) -2 ×106 Vm
(c) Zero
(d) 4 ×106 Vm
(ii) If the current (I) flowing through a circular coil, its radius (R) and number of turns (N) in it are each doubled, magnetic flux density at its centre becomes:
(a) Two times
(b) Four times
(c) Eight times
(d) Sixteen times
(iii) Ratio of the radius of third Bohr orbit to the radius of second Bohr orbit in hydrogen atom is:
(a) 2:3
(b) 4:9
(c) 9:4
(d) 3:2
B. Answer all questions given below briefly and to the point:
(i) A dielectric slab of relative premittivity (i.e. dielectric constant ) is introduced between the two plates of an 8μF air capacitor, in order to completely occupy the space between the two plates. Find the new capacitance of the capacitor.
What is the ratio P1: P2 of electric power deveoloped in R1 and R2 shown in Figure 1 below?
(iii) Current ‘I’ flowing through a metallic wire of area of cross-section ‘a’ is given by the equation I = naevd. What is the meaning of the symbols ‘n’ and ‘vd’?
(iv) State two conditions which must be satisfied in order ito apply Tangent law in magnetism.
(v) A metallic wire carrying a current is kept in a uniform magnetic field, at different angles. At what angle, is the force acting on it maximum?
(vi) What type of wave front is associated with a line source of light?
(vii) Calculate the polarizing angle for glass whose refractive index is 1.6.
(viii) What is the optical power in dioptre of a concave lens of focal length 50 cm?
(ix) What is meant by ‘resolving power’ of a telescope?
(x) How can the defect of short sightedness be corrected?
(xi) Name the series of lines in the hydrogen spectrum which lies in the infrared region.
(xii) Explain the statement: “Half life of Polonium is 3.8 days.”
(xiii) How much matter has to be destroyed to create 9×1013J of energy?
(xiv) In Semi-Conductor Physics, what is LED?
Please refer to attached file for ISC Question Papers 2013 Physics