This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “Dying Stars”.
1. Which process happens inside a star?
a) Electron Excitation
b) Nuclear fusion
c) Nuclear fission
Explanation: Throughout their lives, the stars undergo Nuclear fusion. Hydrogen and helium atoms fuse together to forge heavier elements.
2. When the earth’s sun would die, it would change into a ____________
c) White dwarf
d) Red giant
Explanation: Our sun is a medium-mass star in the universe. Thus, when it would die, it would swell up into a red giant before sloughing off its outer layers.
3. When the hydrogen fuel ends up in a star, it ___________
d) Stops shining
Explanation: When the hydrogen fuel ends up in a star, it contracts under the gravitational force. As it contracts, enough energy is created to use Helium as fuel. The whole process takes millions of years.
4. When the core runs out of hydrogen, the helium is fused into ___________
b) He2+ ions
Explanation: When the core runs out of hydrogen, it contracts. As it contracts, it gets heated up. At some point, the temperature becomes hot enough to fuse Helium into carbon.
5. Black holes are ___________
a) Dead stars
b) Old Supernovas
c) Strong Nebulas
d) Dead planets
Explanation: Black holes are formed when a very massive-star dies. It first bursts into a supernova, which later contracts to a very low volume to form a black hole.
6. In massive stars, when the core has fused carbon into every possible matter, the iron core shrinks from about the size of the earth to 10 Km radius sphere in less than a second.
Explanation: In the given case, the star collapses by its own gravity and the iron core heats up. In less than a second, the iron core, which is about the size of Earth, shrinks to a neutron core with a radius of about 6 miles (10 kilometers).
7. In every nebula, a star is beginning to form.
Explanation: Nebulas are made up of an enormous ball of gas. But, not every nebula is a site of star formation. Some nebulas are created when a star dies. For example, when a sun sized star dies, it creates a planetary nebula.
8. If a star is about 10 times the earth’s sun, how will it change when it’s about to die?
c) Turn into a red giant
d) Turn into a blue giant
Explanation: If the star is much bigger than our Sun, about 10 times as massive, it will likely turn into a blue giant and be able to support fusion reactions in shells in its core when the helium builds up with enough heat and pressure to start fusing the helium into heavier and heavier elements.
Explanation: An average star first becomes a red giant, when hydrogen ends up. Then it changes into a planetary nebular and ultimately becomes a white dwarf. This whole process takes billions of years.
10. Which mathematical quantity is imagined to be present at the center of a black hole?
Explanation: Black hole is defined as a star of zero volume and infinite density. It is believed that at the center of the black holes lies singularity, which can be used to solve the gravity equation.
11. The closest distance the light can go near the black hole and return back is called the ___________
a) Gravitational distance
b) Black hole point
c) Event Horizon
d) Ultimate distance
Explanation: The gravitational pull of a black hole is so much that even light cannot escape from its field. The maximum closes the light can get to the black hole and doesn’t get sucked into it is called the event horizon.
12. According to Stephen Hawking, owing to which process, can the particles escape the field of black hole?
a) Pair production
b) Pair annihilation
c) Compton effect
d) Photoelectric effect
Explanation: According to quantum mechanics, the two particles in a pair may sometimes be wrenched apart before they have a chance to mutually annihilate. When this happens in the region around a black hole, one particle may escape while its antiparticle partner is captured by the black hole.
13. Neutron stars have a mass of ___________
a) 1.4 solar mass
b) 14 solar masses
c) 20 solar masses
d) 30 solar masses
Explanation: A neutron star is the collapsed core of a giant star which before collapse had a total mass of between 10 and 29 solar masses. They have a radius on the order of 10 kilometers and a mass of about 1.4 solar masses.
14. A young star of several solar masses is called as ____________
d) Sirius A
Explanation: Cepheid stars are evolved off the main sequence. They are described as a young star with several solar masses. It pulsates radially, i.e., it’s diameter and temperature keeps varying.
15. The nebula formed when a dying sun sized star begins to shed its outer layer is called as ____________
a) Blue Nebula
b) Crab Nebula
c) Emission Nebula
d) Planetary Nebula
Explanation: A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars when they begin to shed their outer layer.
Sanfoundry Global Education & Learning Series – Engineering Physics.
To practice all areas of Engineering Physics, here is complete set of 1000+ Multiple Choice Questions and Answers.