Top 25 Physics Interview Questions and Answers 2023

Physics Interview Questions and Answers

Physics is one of the most popular branches of Science. It deals with matter and its interaction with the universe. This article will look at some of the questions you should expect in a Physics Interview to increase your chances of landing the job.

1. What is Physics?

Physics is a branch of Science that focuses on matter. It delves into its fundamental composition and behavior through space, time, and motion. As a scientific discipline, Physics aims at understanding the behavior of the universe. It studies objects ranging from the super minute thanks to quantum physics to the entire universe and how it interacts with its constituents.

2. Can You Define Quantum Physics

Quantum physics is one of the most popular branches of physics that explains how everything in the universe works. It explores the nature of fundamental constituents of matter and further delves into how they interact. Quantum physics also explains the working mechanism of Chemistry and Biology, meaning that it is founded on quantum technology, quantum information science, quantum chemistry and quantum field theory. It is worth noting that even though quantum physics is just one of the over ten branches of Physics, it is highly explored.

3. Can You Tell Us the Properties of a Photon

The simplest explanation of a photon is the smallest quantum of electromagnetic radiation. It is, therefore, a fundamental particle of light. It has an array of properties that every physicist should be aware of. First and most importantly, photons move at a constant velocity. They also have no mass and rest energy and are often destroyed or created when exposed to radiation due to absorption or emission. Thirdly, these particles carry energy and momentum with them. Lastly, photons show particle-like interactions when they come across electrons and other particles.

4. What is Quantum Entanglement?

Quantum entanglement is a central principle of quantum physics. As the name suggests, it normally occurs when given particles are intertwined or share spatial proximity. One can use the quantum state of one particle to tell the quantum states of other particles in the linkage. Quantum entanglement can also occur when particles interact or generate. Therefore, these particles stay connected in a way that guarantees that an action performed on any of them has a resultant effect on all the others regardless of the distance.

5. Tell Us the Properties of Plasma

Plasma, also known as the fourth state of matter, is a superheated state of matter in which the electrons are separated or ripped away from the atoms and together form an ionized gas. Common examples are starts, lightning, fluorescent and neon light constituents. It is considered the fourth state of matter alongside liquid, gas and solid and has several properties. First, it doesn’t have a definite shape or volume, given that it is superheated. Second, it is normally found in ionized gases and can be electrically conductive when exposed to free electrical charges not bound to atoms or ions.

6. Define Thermal Conductivity

Thermal conductivity is made up of two words, thermal and conductivity. Thermal refers to anything caused by heat or temperature. It is mostly used to define energy, such as thermal energy. On the other hand, conductivity refers to the rate at which heat passes through a given material.  Therefore, thermal conductivity refers to the ability of a material to conduct heat. Materials with low thermal conductivity experience lesser heat transfer, while those with higher thermal conductivity transfer heat rapidly.

7. What is Parallax?

Parallax is a common effect used by astronomers when calculating the distance to nearby stars. It is also a common effect on physics, referring to the apparent object displacement due to an observer’s viewpoint change. The most common test is viewing an object with one eye shut and viewing the same with both eyes open. The difference in the object position is known as parallax. While measuring the location of stars using parallax, observers or astronomers calculate its apparent change in location after six months to calculate the apparent shift in position. It has proven to work time and again.

8. Define Wave-Particle Duality

Duality means different things in various disciplines. In physics, duality is a concept representing the occurrence of two opposing forces. Wave-Particle duality, therefore, occurs when matter and light show the properties of both waves and particles. A good example is light acting as a wave when shining through narrow spaces or slits while spraying electrons and acting as particles when exposed to a metal surface. This is the easiest explanation and example of lightwave duality that everyone should know.

9. Do You Know What  Dark Matter Is?

Matter is generally defined as anything that occupies space and has weight. However, dark matter comprises two words; dark and matter. Therefore, it refers to any invisible matter such as those space that ensures stars are held well in the galaxy. Unlike other types of matter, dark matter does not have any electromagnetic force effect on them. Therefore, they cannot absorb, emit, or reflect light, hence the term dark, since they are invisible. It is also worth noting that scientists approximate that this matter accounts for over 85% of universe matter, just that it is hidden. It is believed to be composed of subatomic particles that haven’t yet been discovered.

10. What is Heat Resistance?

Heat Resistance, popularly known as thermal resistance, is a heat property in Physics. It measures the temperature difference by which a material resists heat flow, making it the opposite of thermal conductance. It can also be fully defined as the ratio. If the temperature difference between different faces of a material to the rate of heat flow per unit area.  The standard unit of measure for thermal resistance is Kelvin’s per Watt or degrees Celsius per Watt.

11. Define Neutral Buoyancy

Neutral buoyancy is made up of two words: neutral and buoyancy. In Physics, buoyancy refers to the upward force an object submerged in a fluid experience. It is normally exerted by the fluid to oppose the weight of the partially or fully submerged object. An object with a greater buoyancy than its weight normally floats on the liquid. Therefore, a body with neutral buoyancy does not experience the upward force exerted on other objects by the fluids they have been immersed in due to their density. Their buoyancy is normally equal to the pressure exerted on the liquid by the object’s weight.

12. Does Your Weight Affect How High You Can Jump?

To answer this question, we first have to explore what contributes to acceleration. It is the result of force divided by mass, meaning that with the same force, you cannot accelerate yourself as much if you have more mass. This is akin to jumping up with a heavy bag of sand on your back. Therefore, your weight will affect how high you can jump, provided that the leg strength and the jumping technique stays the same. A lighter person will most probably jump higher than a heavier person.

13. Can You Mention Newton’s Laws of Motion

There are three Newton Laws of Motion. The first, the law of inertia, states that a body at rest or in a state of motion remains in the same condition unless acted upon by an external force. The second law states that the rate of change of momentum of a body is equal to the resultant force acting on it in the same direction as its motion. Lastly, for every action, there is an equal and opposite reaction. Additionally, it is worth noting that these three laws do not apply to subatomic particles.

14. Define density

Density, just like mass, is a physical characteristic. It is the measure of mass per unit volume of a given material. It, therefore, measures the amount of matter in a specific volume of a substance. This means that objects with higher densities have more mass per unit of their volume. An object’s average volume is its total mass decided by the total volume. Denser objects normally have lesser volumes than less dense objects with equal masses, such as water.

15. Define the Term Alloy

Alloy is a common term in Physics. It occurs when two or more objects are homogeneously compounded. Alloys are mainly made up of metal and other materials with metallic properties. The resultant material often has unexpected characteristics. It is also worth noting that alloys have different features depending on the number of their constituents. A binary alloy has only two components, whereas a ternary alloy has three. One can also group them depending on their respective methods of formation. Substitution alloys have similar-sized atoms in both pieces, which are often swapped, while interstitial alloys have different-sized bits in their components. Therefore, the smaller particles fit in the spaces between the larger ones.

16. Can You Mention the Three Particles that Make Up an Atom

Atoms are made up of neutrons, protons and electrons, both situated in different positions in the atom. The proton and neutron are normally found in the core or nucleus of the atom, whereas the electrons move around the nucleus at different energy levels. They are therefore situated in the electron cloud. Protons and neutrons are collectively known as nucleons, given their location in the atomic nucleus. They further consist of smaller subatomic particles known as quarks.

17. Can You Tell the Difference Between Isolation and Step Up/Down Transformers?

On many occasions, isolation and step up or step down transformers are physically similar, explaining why many people confuse them. The main difference normally exists in how they are used. In isolation transformers, the wires are connected between each component so that there is no direct contact to permit a leakage current and eliminate unrequired capacitance. In contrast, capacitance exists between the different windings bringing in high outside frequency noises transmitted to the secondary circuits in the normal transformers.

18. Comment about the Arrangement of Atoms in Solids and Liquids

Solids and liquids have different atomic arrangements. This is because atoms cannot move from one location to another in solids due to proximity unless heat or external drive is applied. They are relatively freer in liquids.  It is also worth noting that the atoms of any given solid vibrate rapidly, but the molecules are often locked into position compared to liquids. Solids’ particles are also closer packed than in liquids except for water which has a solid form(ice) that is less dense.

19. Define a Neutron

A neutron is one of the fundamental constituents of an atom, alongside the electron and proton. It is often considered a subatomic particle with an approximate mass of 1.675 × 10–27. It has no electric charge, unlike its counterparts. When free,  the neutron is unstable with a half-life of 886 seconds. It normally ceases to exist after some time if left untouched or unchanged. When released after a decay or fission event, the neutron can be captured by another atomic nucleus in a process known as no-surprise neutron capture. It is also worth mentioning that a neutron has two down quarks and an up quark. On decay, it releases a proton, electron and antineutrino.

20. Will Air Travel be the Same Regardless of the Planes Direction in Relation to the Earth’s Rotation?

No. The time a planet takes to fly from one place to the next greatly relies on the earth’s rotation. Generally, an aeroplane flying from east to west takes less time than its counterparts, regardless of timezones. This also explains why even planes flying from north to south must first calculate the depth of rotational deviance while on a flight. One can also use the earth’s rotation and its effect on a flight to explain why satellites appear stationary while, in the real sense, they are travelling at the speed of the earth’s rotation.

21. Do You Know What Normally Happens When One Travels Across the Dateline?

When travelling west, the day will automatically change to the next day, given that areas west of the prime meridian are always head in time. When travelling east, it moves to the day before because of the same reason-areas east of the prime meridian are always behind in time. Even though it sounds a bit confusing, it is a simple concept.

22. What Do You Know about Tensile Strength

Tensile strength comes from the word tension. Therefore, it is the ability of a given material to resist breakage due to stress. It can also be defined as a given point in which a material fails when tensile strength is applied. Instead of being calculated, tensile strength is measured in Newton per square meter, which also considers strength and stress. It can also be measured in Pascal, abbreviated as Pa. It is also worth noting that some materials such as steel have extremely high tensile strengths, normally measured in millions of Pa.

23. Why is it Necessary for Pilots to Inwardly Tilt the Outer Wing of an Airplane When Turning?

Balancing a plane requires tact and an enhanced understanding of Physics. Two control surfaces are involved when a plane turns, the ailerons found on the edge of the wings and the rudders located vertically at the back of the aircraft. When the ailerons move in the opposite direction, the plane tilts, lifting the wings and causing a turn instead of upward acceleration. The rudder will turn the aircraft to different sides, left and right but cannot independently change its direction. The outer ring of the plane must therefore tilt inward when turning to engage these two surfaces since turning can’t be achieved separately.

24. Walk Us Through How One Can Convert Pascal to Torr

Both Pascal and Torr are used to measure pressure. However, torr measures pressure based on an absolute scale and is part of the International Systems of Unitel, popularly known as SI units. On the other hand, Pascal is smaller than Torr even though it also measures pressure. There are 133.32 Pascal per Torr, meaning that to convert a given Pascal value to Torr, all you need to do is divide the Pascal measurement by 133.32. To convert a Torr measurement to Pascal, multiply it by 133.32.

25. Can You Define Free Fall Acceleration

As the name suggests, freefall acceleration refers to the acceleration of a given body as it falls in a vacuum or the earth’s surface in its gravitational field. In simple terms, the freefall acceleration of a body is the acceleration caused by the earth’s gravity when not acted upon by an external force such as resistance. Earth’s freefall acceleration is 9.81 meters per second or 32.2ft/s minus air resistance.


These 25 recommendations sum up some of the questions you are likely to be asked in a Physics Interview. Convince the interviewer that you are highly knowledgeable on different Physics concepts and will exceed expectations if given a chance. Do not forget to work on the first impression, as it dictates the interview results outrightly.

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