General Science Physics Questions
41. Chandrashekhar Limit, postulated by Dr S. Chandrashekhar posts a limit of mass of which among the following?
[A] Neutron Star
[B] White Dwarf
[C] Steller Black Hole
[D] Young stellar object
[B] White Dwarf
Notes:
In 1931, the astrophysicist Subrahmanyan Chandrasekhar theorised that a star would not form a stable white dwarf at the end of its life if its mass was greater than 1.44 times the solar mass (1.44 Ms). This is known as the Chandrasekhar limit, above which the white dwarf will explode as what is called a “Type 1a supernova”. This work fetched Chandrasekhar the Nobel Prize in 1983.
42. What is the use of Venturimeter?
[A] To measure subdivisions of scale
[B] To measure wavelength of radio wave
[C] To measure friction
[D] To measure rate of flow of fluids
[D] To measure rate of flow of fluids
Notes:
A Venturimeter is the device used to measure rate of flow of fluids. This device is based on the principle of Bernoulli’s Equation.
43. In which of the following conditions, a Balloon filled with a gas such as Hydrogen will tend to rise up?
[A] If the buoyant force exerted by the air on a balloon is greater than the weight of the balloon
[B] If the buoyant force exerted by the air on a balloon is less than the weight of the balloon
[C] If the buoyant force exerted by the air on a balloon is equal to the weight of the balloon
[D] If the density of the air is greater than the density of the gas filled in balloon
[A] If the buoyant force exerted by the air on a balloon is greater than the weight of the balloon
Notes:
A balloon filled with a gas such as hydrogen gas is much lighter in weight than the weight of air displaced by it. So the buoyant force exerted by the air on a balloon is greater than the weight of the balloon. The hydrogen gas which is lighter than air enables the balloon to float.
44. Who among the following discovered X-rays?
[A] Marie Curie
[B] J.J Thomson
[C] W.C Roentgen
[D] James Chadwick
[C] W.C Roentgen
Notes:
X-rays were discovered by Wilhelm Conrad Roentgen. W.C Roengten discovered X-Rays while actually working on Cathode rays. X-rays is a form of electromagnetic radiation having a wavelength ranging from 0.01 to 10 nanometers and frequencies in the range 30 petahertz to 30 exahertz. Some Uses of X-Rays: The main use of X-rays is in medicine to check for a broken bone inside body. X-rays can also be used to kill cancer cells. X-rays are used at security checks at airports, railway stations etc. to check customers and baggage. X-rays are also used art historians to see if a picture has been painted on top of an older one. X-ray diffraction is also very important in spectroscopy and as a basis for X-ray crystallography.
45. What is the change in the angular momentum of a system as per the Law of Conservation of Angular momentum, if the total external torque acting is zero?
[A] Remains constant
[B] Becomes zero
[C] Increases exponentially
[D] None of the above
[A] Remains constant
Notes:
Law of Conservation of Angular Momentum: if the total external torque acting on a system is zero, the angular momentum of a system remains constant. Angular Momentum is the momentum associated with the rotation of an object. Angular Momentum = moment of Inertia X angular Speed.
46. Which of the following is true about displacement of an object?
- [A] It is always equal to the distance travelled by the object
[B] It can be less than the distance travelled by the object - [C] It can be greater than the distance travelled by the object
- [D] It always less than the distance travelled by the object
[B] It can be less than the distance travelled by the object
Notes:
The displacement is the shortest distance between the initial and final position of an object in the given time. The displacement of an object is a vector quantity. It can be less than or equal to the distance but can never be greater than the distance travelled by that object.
47. Which of the following represents non-uniform motion?
[A] Equal displacements in unequal intervals of time
[B] Unequal displacements in unequal intervals of time
[C] Equal displacements in equal intervals of time
[D] Unequal displacements in equal intervals of time
[A] Equal displacements in unequal intervals of time
Notes:
An object is said to be in non-uniform motion if it undergoes equal displacements in unequal intervals of time. In non-uniform motion, the velocity is different at different instants.
48. What is the dimensional formula of work done?
[A] M1 L1 T-1
[B] M1 L2 T-1
[C] M1 L-1 T-2
[D] M1 L2 T-2
[D] M1 L2 T-2
Notes:
The dimensional formula of work done is M1 L2 T-2. Work is said to be done by a force when the body is displaced actually through some distance in the direction of applied force. The S.I unit of Work is joule.
49. What is the value of Universal Gravitational Constant?
[A] 6.67×10-9 N–m2 kg–2
[B] 6.67×10-10 N–m2 kg–2
[C] 6.67×1011 N–m2 kg–2
[D] 6.67×10-11 N–m2 kg–2
[D] 6.67×10-11 N–m2 kg–2
Notes:
The value of Universal Gravitational Constant is same throughout the universe and is equal to 6.67×10-11 Nm2 kg-2 in S.I. and 6.67×10-8 dyne cm2 g-2.
50. Which of the following condition will be true for a planet to have atmosphere?
[A] Velocity of molecules in its atmosphere is lesser than escape velocity
[B] Velocity of molecules in its atmosphere is greater than escape velocity
[C] Velocity of molecules in its atmosphere is twice the escape velocity
[D] Velocity of molecules in its atmosphere is equal to the escape velocity
[A] Velocity of molecules in its atmosphere is lesser than escape velocity
Notes:
A planet will have atmosphere if the velocity of molecule in its atmosphere is lesser than escape velocity. This is why earth has atmosphere while moon has no atmosphere.
