41. A body starts from rest at time t = 0, the acceleration time graph is shown in the fig. The maximum velocity attained by the body will be

a) 110 m/s b) 55 m/s

c) 650 m/s d) 550 m/s

Ans : b)

Maximum velocity = area under the graph = 55 m/s

42. A source emits sound of frequency 600 Hz inside water. The frequency heard in air will be equal to (velocity of sound in water = 1500 m/s, velocity of sound in air = 300 m/s)

a) 3000 Hz b) 120 Hz

c) 600 Hz d) 6000 Hz

Ans: c)

43. If liquefied oxygen at 1 atmospheric pressure is heated from 50 k to 300 k by supplying heat at constant rate. The graph of temperature vs time will be

a) b)

c) d)

Ans :c)

44. Six identical resistors are connected as shown in the fig. The equivalent resistance will be

a) maximum between P and R

b) Maximum between Q and R

c) maximum between P and Q

d) all are equal

Ans: c)

45. In a photoelectric experiment anode potential is plotted against plate current

a) A and B will have different intensities while B and C will have different frequencies

b) B and C will have different intensities while A and C will have different frequencies

c) A and B will have different intensities while A and C will have equal frequencies

d) A and B will have equal intensities while B and C will have different frequencies

Ans : a)

46. Pressure depends on distance as, , where , are constants, z is distance, k is Boltzman's constant and is temperature. The dimension of are

a) b)

c) d)

Ans: c)

should be dimensions, hence

hence

47. An electron travelling with a speed u along the positive x-axis enters into a region of magnetic field where . It comes out of the region with speed v then

a) b)

c) d)

Ans: b)

Charged particle will move in a circular path with constant speed inside the magnetic field.