NUMS MDCAT Past Paper Dated: 2019

61- If the wave length of K X-ray from Cu is ≈ 1.337 × 10⁻¹⁰ m, then the energy difference between two levels from which transition results will be:

A. 9.03 keV
B. 9.90 keV
C. 8.03 keV
D. 10.0 keV

Answer : A. 9.03 keV

62- An alternating voltage source is connected to a resistor R, and a capacitor C, then which of the following statement about phase between voltage V and current I is correct?

A. In Resistance I leads V by 90°, In Capacitor I leads V by 90°
B. In Resistance I lags V by 90°, In Capacitor I leads V by 90°
C. In Resistance I and V are in phase, In Capacitor I leads V by 90°
D. In Resistance I and V are in phase, In Capacitor I lags V by 90°

Answer : C. In Resistance I and V are in phase, In Capacitor I leads V by 90°

63- A D.C power supply is connected in series to a resistor R = 3Ω and a capacitor of capacitance C = 1F. If emf of battery is 9V, then values of Maximum charge Q₀ on each plate of capacitor and time t required to obtain this maximum charge Q₀ will be:

A. Q₀ = 1C and t = 3s
B. Q₀ = 3C and t = 2s
C. Q₀ = 9C and t = 3s
D. Q₀ = 3C and t = 1s

Answer : C. Q₀ = 9C and t = 3s

64- Radiation emitted from a certain star has maximum intensity near the wavelength λ = 580 nm. Assuming star as a black body, then temperature of its surface is:

A. 5000K
B. 6000K
C. 6500K
D. 7000K

Answer : A. 5000K

65- A capacitor and an inductor are connected to A.C supply. If we double the frequency of A.C supply then the effect on reactance of capacitor XC and reactance of inductor XL will be:

A. Both XC and XL are doubled
B. Both XC and XL are halved
C. XC is doubled and XL reduces to half
D. XL is doubled and XC reduces to half

Answer : D. XL is doubled and XC reduces to half

66- A body of mass 2kg executes a SHM under a force of F = (1 N/m³) x. If its velocity at mean position is 100 m/s, the value of its amplitude is:

A. 100m
B. 10m
C. 140m
D. 500m

Answer : C. 140m

67- Unit of magnetic flux is weber (WB). In terms of S.I. base units, weber can be written as:

A. NmA
B. N⁻¹m⁻¹
C. NmA⁻¹
D. NmA²

Answer : C. NmA⁻¹

68- A block of mass 20 g is thrown vertically upward with a speed of 10 m/s. The work done by the force of gravity during its upward motion is:

A. 1000 J
B. -1000 J
C. 1J
D. -1J

Answer : D. -1J

69- The resistance of a wire is 6 Ω at 50°C and 8 Ω at 100°C. The resistance of wire at 0°C will be:

A. 1 Ω
B. 2 Ω
C. 3 Ω
D. 4 Ω

Answer : D. 4 Ω

70- An electric bulb is marked 200 W, 220V. If the same bulb is connected to 110 V-supply line, the power consumed by it is:

A. 25 W
B. 50 W
C. 75 W
D. 100 W

Answer : B. 50 W

71- If the magnitude of the sum of two vectors is equal to the magnitude of the difference between two vectors, then what will be the angle between these vectors?

A. 15°
B. 30°
C. 45°
D. 90°

Answer : D. 90°

72- A cathode ray oscilloscope is displaying an AC signal. If one wave is complete on a 2 cm along X-axis and time-base setting is 10 ms/cm, then frequency of AC signal will be:

A. 20 Hz
B. 50 Hz
C. 100 Hz
D. 200 Hz

Answer : B. 50 Hz

73- Two bodies are projected with angle of a and (90 - a) to the horizontal with the same speed. The ratio between their time of flight is:

A. Sin a : 1
B. Sin a : cos a
C. cos a : Sin a
D. Sin a : tan a

Answer : B. Sin a : cos a

74- A particle having mass m and charge q, moves in a circular path in a magnetic field of strength B. If the radius of the circular path is r, the time required by this particle to complete one revolution is:

A. 2πm/qB
B. k × n/r × r
C. qrB/m
D. 2πm/rB

Answer : A. 2πm/qB

75- If M and m represent the mass of Earth and mass of a satellite respectively; then the orbital speed v of satellite in a circular orbit of radius r around earth will be:

A. V = GM/r
B. V = √(GM/r)
C. V = √(r/GM)
D. V = √(2GM/r)

Answer : B. V = √(GM/r)

76- A 2μF capacitor is connected to 10V dc supply. If 'Q' represents the charge on each plate and 'E' the energy stored on each plate, which of the following represents the values of Q and E?

A. Q = 20μC and E = 50μeV
B. Q = 10μC and E = 100 eV
C. Q = 10μC and E = 500 eV
D. Q = 20μC and E = 100 μJ

Answer : D. Q = 20μC and E = 100 μJ

77- Two strings A and B of a sitar produce 5 beats per second. When a tension in string B is slightly increased, 2 beats per second produced. If the frequency of string A is 400 Hz, then real frequency of string B was:

A. 285 Hz
B. 302 Hz
C. 395 Hz
D. 401 Hz

Answer : C. 395 Hz

78- If N, m, v and c represents number of molecules, mass of a molecule, volume of cubical container and speed of a molecule respectively. Then by using the method of dimensions, check which of the following expressions represents the pressure (p) of a gas?

A. P = (1/3)(Nm/v²)
B. P = (1/3)(v²/v²)
C. P = (1/3)(Nm/v)
D. P = (1/3)(Nm²/v)

Answer : A. P = (1/3)(Nm/v²)

79- Moment of inertia of a thin rod of mass m, length l about a line passing through its center is:

A. ml²
B. (1/2)ml²
C. (1/3)ml²
D. (1/12)ml²

Answer : D. (1/12)ml²

80- Using the concept of significant figures, the sum and product of three numbers 4.342, 3.02 and 2.0 were calculated. Which of the following choice is most accurate?

A. Product = 26.2 & Sum = 9.3
B. Product = 26.23 & Sum = 9.36
C. Product = 26.226 & Sum = 9.362
D. Product = 26.22568 & Sum = 9.362

Answer : A. Product = 26.2 & Sum = 9.3

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