Theory of relativity substitutes the generic idea of force which attracts objects to one another with gravity curving or warping space. It relates the way things look in one frame of reference to how they look in another, the stretching of time and space, and increase in mass.Theory of relativity combines two interrelated theories by Albert Einstein - special relativity and general relativity.
Question 1: Space-time reference comprises _________ coordinates as a frame of reference.
a) two b) three
c) four d) infinite
Answer: c) four
Explanation: Space-time references have four coordinates of x, y, z and t. It plays a major role in Einstein’s special theory of relativity.
Question 2: According to Einstein’s theory of relativity, as an object approaches the speed of light, its mass becomes __________.
a) negligible b) unity
c) remains same d) infinite
Answer: d) infinite
Explanation: For an object in motion,
As v approaches c, the speed of light, the denominator, becomes zero. Therefore the mass of the object becomes infinite.
Question 3: The momentum of a photon having energy 10-16J is __________.
Explanation: Rest mass of a photon is zero.
Therefore, momentum. P=E/c
Question 4: According to Einstein's special theory of relativity, formulations of the laws of Physics are equivalent to ______________.
a) inertial frame of reference b) non-inertial frame of reference
c) both (a) and (b) d) none of these
Answer: a) inertial frame of reference
Explanation: One of the postulates of Einstein’s special theory of relativity states that all the inertial frames of reference are equivalent to the formulations of physics.
Question 5: According to the special theory of relativity, _______ and ______ are not an absolute quantity.
a) mass, height b) speed, time
c) height, speed d) mass, time
Answer: d) mass, time
Explanation: Since there is no absolute frame of reference, mass and time are not an absolute quantity.
Question 6: Magnetic field and Electric field are ____________ in the theory of relativity.
a) dependent b) independent
c) interdependent d) none of these
Answer: c) interdependent
Explanation: Magnetic field and electric field are part of one unified entity; electromagnetism. Therefore they are interdependent.
Question 7: Which of the following is the correct expression for dilation factor?
Explanation: In the theory of relativity, time dilation is the phenomenon of time passing slower for an observer who is moving relative to another observer. It is given by
Question 8: Which transformation was replaced by the Lorentz transformation which confirmed the postulate of relativity?
a) Maxwell b) Plancks
c) Newton d) Galelian
Answer: d) Galelian
Explanation: Galelian transformation is the method transforming the coordinates of two reference frames that differ by a certain constant relative motion.
Question 9: Which of the following forces acts on a charged particle in an electromagnetic field?
a) Electromagnetic force b) Lorentz force
c) Magnetic force d) None of these
Answer: b) Lorentz force
Explanation: The force exerted on charged particles in an electromagnetic is known as Lorentz force.
Question 10: In which direction does the length contraction happen?
a) perpendicular to the motion b) parallel to the motion
c) along the direction of motion d) none of these
Answer: c) along the direction of motion
Explanation: Length contraction is a phenomenon of decrease in length detected by an observer that travels at a non-zero velocity relative to the observer along the direction of motion.