Physics MCQs

Notes:
Astigmatism is due to imperfect spherical nature of eye lens. The focal length of eye lens is in two orthogonal directions become different so they cannot see objects in two orthogonal directions simultaneously. This defect in direction can be removed by using cylindrical lens in a particular direction.

Notes:
The Vernier caliper has a main scale and a sliding vernier scale which can measure nearest to 0.02 mm. It can be used to measure internal and the external dimensions of an object by using the smaller jaws at the top and the main jaws respectively. By using stems depth can be measured.

Notes:
Conservation of Linear Momentum law says that if no external force acts on a system, then its total linear momentum remains conserved. In equation form, Momentum=mass*velocity. To increase the momentum of an object, we need to either increase its mass or velocity or both.

• Rockets work on law of conservation of momentum. As momentum in one direction is given to the rocket’s exhaust gases, momentum in the other direction is given to the rocket itself.

Notes:
Voltmeter is an instrument for measuring electric charge or electrical potential difference. It was invented by Hans Christian Oersted.

Notes:
The joule is the unit of energy in the International System of Units. It is equal to the work done on an object when a force of one Newton acts on that object in the direction of the force’s motion through a distance of one meter. One joule of work is said to be done when a force of 1 N causes a displacement of 1 m.

Notes:
nautical mile is a unit of length. 1 nautical mile is equal to 1.852 x 1000 m Other important units of length are:

• 1 mile = 1.609 x 1000 m
• 1 light year = 9.46 x 10¹⁵ m
• 1 AU = 1.5 x 10¹¹m
• 1 Par sec = 3.1 x 10¹⁶m

Notes:
Joule is the unit of Pressure energy. Pressure energy is the energy stored in a fluid due to the force per unit area applied onto it Pressure energy = Pressure x volume Its dimensional formula is M L² T^-2

Notes:
Kinetic energy of a body is half the product of mass of the body and square of the velocity of the body. K.E = 1/2(mv²) Kinetic energy depends on the frame of reference. Kinetic energy of a body is always positive.

Notes:
The unit of intensity of Gravitational field in the c.g.s system is dyne g^-1 or cm s^-2. S.I. unit of intensity of Gravitational field is N Kg^-1 m s^-2.

Notes:
In this case, the radius of the orbit will be nearly equal to the radius of earth. The orbital velocity of a satellite orbiting very close to the surface of earth is 7.92 km/s.