Solution - Career Point

combination. The terminal voltage of the cells A, B,C are1.5 V 1.5 VA1Ω B 1Ω1.5 V 1ΩC(A) 1, 1, 2 (B) 1.5, 1.5, 1.5(C) 1.5, 0, 0 (D) 2, 1, 111. A wire has resistance of R ohm at T kelvin. At whattemperature the resistance of wire be 2R ohm whentemperature coefficient of resistance is α per degreecentigrade.(273 − T) α + 1 (273 − T) α −1(A)(B)2α2α(273 − T) α −1(273 − T)2α + 1(C)(D)αα12. Two cells each of same emf but of internal resistancer 1 and r 2 are joined to form a series circuit through anexternal resistance R. Value of R in term of r 1 and r 2for which cell 1 has zero p.d. across it isE E1r 1 r22(A) R = r 1 – r 2 (B) R = r 1 + r 2r1r2r 1 + r2(C) = R (D)r + rr r= R12R1 213. A current i flows in the network shown. Resultingmangnetic induction at point p isA F aPaaa2aBµ(A) 04πia8 µ 0i(C) –2 πaE2aaa2µi(B) – 08πa2 µ i(D) 08 πa14. An alpha particle and a proton have same velocitywhen they enter a uniform magnetic field. The periodof rotation of proton will beDC(A) double of that of α particle(B) four times that of α particle(C) one half time that of α particle(D) same as that of α particle15. A coil of inductance 8.4 mH and resistance 6 Ω isconnected to a 12 V battery. The current in the coil is1A at approximate time(A) 500 s (B) 20 s (C) 35 ms (D) 1 ms16. A fish rising vertically up towards the surface withspeed 3ms –1 observe a bird diving vertically downtowards it with speed 9 m/s. The actual velocity ofbird is(A) 4.5 ms –1 (B) 5.4 ms –1(C) 3.0 ms –1 (D) 3.4 ms –117. A concave lens of glass, refractive index 1.5 has bothsurface of same radius of curvature R. on immersion ina medium of refractive index 1.75, it will behave as a(A) convergent lens of focal length 3.5 R(B) convergent lens of focal length 3R(C) divergent lens of focal length 3.5 R(D) divergent lens of focal length 3 R18. I is the intensity due to source of light at any point Pon the screen if light reaches the point P via twodifferent paths (a) direct (b) after reflection from aplane mirror then path difference between two pathsis 3λ/2, the intensity at P is(A) I (B) zero (C) 2I (D) 4I19. The surface of some material is radiated, in turn, bywaves of λ = 3.4 × 10 –7 m and λ = 5.4 × 10 –7 mrespectively. The ratio of stopping potential in twocases is 2 : 1, the work function is(A) 2.05 eV (B) 1.05 eV(C) 3.05 eV (D) None20. A X-ray tube has a working voltage of 40 × 10 3 V.The continuous spectrum limit of the emitted x-rays is(A) 0.17 Å (B) 0.13 Å (C) 0.13 Å (D) 0.31 Å21. The number of alpha and beta deca 88Ra 222experiences before turning into stable Pb 206 isotope is(A) 4, 2 (B) 2, 4 (C) 1, 3 (D) 6, 10yy´XtraEdge for IIT-JEE 77APRIL 2010