May 2011 - Career Point

Ans.Sol.(A) 2E 0 a 2(C) E 0 a 2[C]z2(B) 2 E 0 aE a20(D)2⎛ V + V ⎞ν′ =⎜0⎟ ν⎝ V − Vs′ ⎠⎛ 320 + 10 ⎞= ⎜ ⎟ 8 KHz⎝ 320 −10⎠330= × 8 = 8.51 KHz310(a,0,a)x(a,a,a)(0,0,0) (0,a,0)yzF(0,0,a) G (0,a,a)28. A meter bridge is set-up as shown, to determinean unknown resistance 'X' using a standard 10ohm resistor. The galvanometer show null pointwhen tapping-key is at 52 cm mark. The endcorrectionsare 1 cm and 2 cm respectively for theends A and B. The determine value of 'X' is-X10ΩE(a,0,a)xD(a,0,0)AH(a,a,a)C (a,a,0)flux through EHBA= flux through EHDC= E 0 a 2B(0,a,0)27. A police car with a siren of frequency 8 kHz ismoving with uniform velocity 36 km/hr towards atall building which reflects the sound waves. Thespeed of sound in air is 320 m/s. The frequencyof the siren heard by the car driver is-yA(A) 10.2 ohm(C) 10.8 ohmAns. [B]x 52 + 1Sol. =10 48 + 253×10= = 10.650B(B) 10.6 ohm(D) 11.1 ohm29. A 2 µF capacitor is charged as shown in figure.The percentage of its stored energy dissipatedafter the switch S is turned to position 2 is-1 2VS2µF 8µF(A) 8.50 kHz(B) 8.25 kHz(C) 7.75 kHz(D) 7.50 kHzAns. [A]Sol.336 × 10V s =3600m/s = 10 m/s, ν = 8 KHzV 0 = 320 m/sV 0 = V s = 10 m/sV sObserverAns.Sol.(A) 0 % (B) 20 %(C) 75 % (D) 80 %[D]2µF8µFXtraEdge for IIT-JEE 67 MAY 2011