2.AIPMT question paper 2010 mains - AIPMT 2013

20. A condenser of capacity C is charged to apotential difference of V 1. The plates of thecondenser are then--------⎡C2 2Ans: ( V 1 − V2)⎢⎣ L1/ 2⎤⎥⎦1 2Sol: U 1 = CV 121 2U 2 = CV 221 21 2 2i L = UL= U1− U2= C V1− V2221/ 2⎡C2 2 ⎤⇒ i = ⎢ ( V 1 − V2)L⎥⎣⎦( )21. Two parallel metal plates having charges +Q and−Q face each other at a certain distance--------25. When monochromatic radiation of intensity Ι fallson a metal surface, the number --------Ans:Sol:2 N and TΙ ∝ NT depends only on work function andfrequency.26. The electron in the hydrogen atom jumps fromexcited state (n = 3) to its ground state (n = 1)--------Ans:7 VSol: E 3 =−13.6= −1.51 eV23E = E 3 − E 1 = −1.51 − (−13.6)= 7 eV∴ V = 7 VAns:decrease27. The binding energy per nucleon in deuterium andhelium nuclei are --------Sol:E’ = KE ⇒ decreasesAns:23.6 M eV22. The electric field at a distancecentre of a charged--------Ans:Sol:Zero3 Rfrom the2E = 0 at any point inside a charged shell.23. The thermo emf E in volts of a certainthermocouple is found--------Ans: 225 °CdE 2θSol: = 30 − = 0dθ1530 ×15⇒ = θ2i.e. θ = 225 °CSol:2241 H + 1 H = 2He+ Q∴ Q = (4 × 7) − 4 × 1.1 = 23.6 M eV28. The decay constant of a radio isotope is λ. If A 1and A 2 are its activities at times t 1 and --------Ans:( A 1 A )− 2λASol: A 1 = |λN 1| ⇒ N 1 = 1λAA 2 = |λN 2| ⇒ N 2 = 2λA 1 − A 2λN = (N 1 − N 2) = ( )29. For transistor action:--------Ans: The base region must be very thin andlightly doped.24. A particle having a mass of 10 −2 kg carries acharge of --------Sol:(b) is correct(c) is correct→ →Ans: Both B and E should be along thedirection of velocity.30. The following figure shows a logic gate circuitwith two inputs A and B and the--------Sol:(b) and (c) are correct.Ans:NAND GATENote (c) will be correct only ifother choices is correct.E = v . NoBSol:Gives high output when any of the inputsare zero and a low output only when bothinputs are high ⇒ NAND GATE.