Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
31. Domestic electrical wiring refers basically to which of the following connections?
[A] Series connection
[B] parallel connection
[C] combination of series and parallel connections
[D] series connection within each room and parallel connection elsewhere
Show Answer
Correct Answer: B [parallel connection]
Notes:
Domestic electrical wiring is basically a parallel combination because when appliances are connected in a parallel attach men each of them can be put on or off independently.
32. What are the applications of cryogenics or low temperatures?
[A] Space Travel, Surgery and Magnetic Levitation
[B] Surgery, Magnetic Levitation, and Telemetry
[C] Space Travel, Surgery, and Telemetry
[D] Space Travel, Magnetic Levitation, and Telemetry
Show Answer
Correct Answer: A [Space Travel, Surgery and Magnetic Levitation]
Notes:
Cryogenics involves the study and application of very low temperatures. Its usage spans across sectors, from space travel to medical science. In space travel, cryogens like liquid hydrogen and oxygen help to propel rockets. In surgeries, a technique called cryosurgery uses such temperatures to constrict blood vessels, hence controlling blood loss. In the technologically advanced field of magnetic resonance imaging (MRI), cryogens like liquid helium are used to cool the coils in order to generate strong magnetic fields. This field is key in detecting proton relaxation, providing the much-needed imagery for diagnostics.
33. When water is heated from 0°C to 10°C, what will happen to its volume?
[A] increases
[B] decreases
[C] does not change
[D] first decreases and then increases
Show Answer
Correct Answer: D [first decreases and then increases]
Notes:
Initially at start of heating from 0°C to 4°C there will be a contraction as a result of which volume decreases. On further heating beyond 4°C to 10°C the molecules gain kinetic energy and start moving more randomly. Thus, intermolecular distance increases as a result of which its volume increases.
34. What is rate of change of displacement?
[A] Velocity
[B] Acceleration
[C] Deceleration
[D] Angular momentum
Show Answer
Correct Answer: A [Velocity]
Notes:
Rate of change of displacement is called velocity and rate of change of velocity is called acceleration.
35. The atmospheric air is held to the Earth by?
[A] gravity
[B] winds
[C] clouds
[D] rotation of the Earth
Show Answer
Correct Answer: A [gravity]
Notes:
The atmosphere is held in place on earth by gravity.
36. If the temperature of a liquid is 32° F, what is its temperature in Celsius scale?
[A] 32° C
[B] 0° C
[C] 100° C
[D] 212° C
Show Answer
Correct Answer: B [0° C]
Notes:The formulas for converting between degree Celsius and degree Fahrenheit are
37. Which of the following is not a vector quantity?
[A] Momentum
[B] Displacement
[C] Torque
[D] Speed
Show Answer
Correct Answer: D [Speed]
Notes:
Speed is a scalar quantity that measures the rate at which an object changes its position. It refers only to how fast an object is moving, without any information about the direction. On the other hand, momentum, displacement, and torque are all vector quantities. They require both a magnitude and direction to fully describe them. Therefore, out of the options, speed is the one that is not a vector quantity.
38. The rate of change of displacement with time is known as__:
[A] Force
[B] Acceleration
[C] Retardation
[D] Velocity
Show Answer
Correct Answer: D [Velocity]
Notes:
The rate of change of displacement of an object (displacement over elapsed time) is velocity. Velocity is a vector since it has both magnitude (called speed) and direction.
39. If the acceleration due to gravity on the surface of earth is g, then the acceleration due to gravity on the surface of a planet whose mass is same as that of earth and radius is twice as that of earth is__:
[A] g/4
[B] g/2
[C] 4g
[D] 2g
Show Answer
Correct Answer: A [g/4]
Notes:
Acceleration due to gravity is given by the formula : g = GM/r2 According to the question, mass of the second planet is same as that of earth and radius is twice So, using the formula of g, we get the acceleration due to gravity of the second planet as g/4.
40. Water is used in hot water bags because__:
[A] It is easily obtained
[B] It is cheaper and is not harmful
[C] It has high specific heat
[D] It is easy to heat water
Show Answer
Correct Answer: C [It has high specific heat]
Notes:
The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The specific heat of water is 1 calorie/gram°C = 4.186 joule/gram°C which is higher than any other common substance. As a result, water plays a very important role in temperature regulation to be used in hot water bags.
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