25 questions on “Physics GK Mock Test” objective questions series.

This article is important for anyone who is preparing for civil services, Bank PO exam or other government exams as such questions have been asked in all these exams in general studies or general knowledge section.

Question Section:

Que (151): ‘Parsec’ is the unit of measurement of which distance?
A. Astronomical distance
B. Cosmological distance
C. Galaxy distances
D. Space distances

Ans: Astronomical distance,

It stands for “parallax of one arcsecond” and is commonly used in astronomy to describe distances to celestial objects beyond our solar system.

The parsec is equivalent to approximately 3.26 light-years (about 31 trillion kilometers or 19 trillion miles). It is based on the principle of parallax, a method used to measure distances to nearby stars.

Que (152): The light coming from stars gives the idea of their which quality?
A. Intensity
B. Heat
C. Luminosity
D. Size

Ans: Temperature,

The light coming from stars gives astronomers valuable information about their “luminosity” or brightness. Luminosity is a measure of the total amount of energy radiated by a star per unit of time, typically expressed in terms of the Sun’s luminosity (L☉). It represents the intrinsic brightness of the star, regardless of its distance from Earth.

Que (153): How does Transfer of heat energy from the sun to the moon take place?
A. Through the medium air
B. Through heat
C. Through humidity

Unlike on Earth, which has an atmosphere that can transfer heat through conduction and convection, the Moon lacks a substantial atmosphere. Therefore, radiation is the primary mechanism by which heat is transferred from the Sun to the Moon.

Radiation is a form of energy transfer that occurs through electromagnetic waves, such as visible light, infrared radiation, and ultraviolet radiation. The Sun emits a vast amount of electromagnetic radiation across a wide spectrum, including visible light.

Que (154): When does Super conductivity result?
A. When matter is cooled to very low temperature
B. When matter is cooled to a temperature
C. When matter is cooled to average temperature
D. When matter is cooled to high temperature

Ans: When matter is cooled to very low temperature,

Superconductivity results when certain materials exhibit a complete loss of electrical resistance and the expulsion of magnetic fields at extremely low temperatures. In a superconducting state, electric current can flow through the material without any loss of energy due to resistance, leading to zero electrical resistance.

Que (155): When the temperature increases, what happens to the angle of contact of a liquid?
A. Increases
B. Decreases
C. Remains constant
D. none of these

Ans: Decreases,

The angle of contact refers to the angle formed at the interface between the liquid, solid, and the surrounding gas (usually air).

The angle of contact depends on the balance of adhesive forces (between the liquid and solid) and cohesive forces (within the liquid). It is influenced by various factors, including the nature of the liquid and solid, the properties of the surface, and the temperature.

Que (156): Why does the velocity of rain drop attain constant value?
A. Viscous force exerted by air
B. Force by which it is released
C. Gravitational force
D. Blowing winds

Ans: Viscous force exerted by air,

The velocity of a raindrop attains a constant value due to the balance between two opposing forces acting on the raindrop as it falls through the atmosphere.

Gravity pulls the raindrop downward, causing it to accelerate as it falls. The force of gravity is proportional to the mass of the raindrop and acts in the downward direction.

As the raindrop moves through the air, it encounters resistance due to air molecules colliding with its surface. This resistance is known as air resistance or drag force. The magnitude of the drag force depends on the speed of the raindrop and the shape and size of the raindrop. At low speeds, the drag force is relatively small, but as the speed increases, so does the air resistance.

Que (157): The focal length of a convex lens is 50 cm. What is its power?
A. 1D
B. 2D
C. 3D
D. 4D

Ans: 2 D,

The power of a lens is given by the formula:

Power (P) = 1 / F

where F is the focal length of the lens in meters.

In this case, the focal length (F) of the convex lens is 50 cm, which is equal to 0.50 meters (since 1 meter = 100 cm).

Now, we can calculate the power of the convex lens:

Power (P) = 1 / 0.50 = 2 diopters (D)

Therefore, the power of the convex lens is 2 diopters.

Que (158): Energy transferred to a person through gamma rays is measured in by which unit?
A. Conduction
B. Convection
D. Roentgens

Ans: Roentgens,

The roentgen is a unit of exposure to ionizing radiation and quantifies the amount of ionization produced in air by gamma rays or X-rays.

One roentgen (1 R) is defined as the amount of radiation that produces one electrostatic unit of charge (approximately 2.58 x 10^(-4) coulombs) of either sign in one cubic centimeter of dry air at standard temperature and pressure (STP).

Que (159): Which field is used to produce deflection in a television picture tube?
A. A Electromagnetic field
B. An Electrostatic field
C. A frictional field
D. A gravitational field

Ans: A Electromagnetic fields,

In a television picture tube, the field used to produce deflection and control the position of the electron beam is the “electromagnetic field.”

The television picture tube, also known as a cathode-ray tube (CRT), works based on the principle of electron beam deflection. The CRT consists of an electron gun that emits a focused beam of electrons. This electron beam is accelerated toward the front of the tube and directed towards a phosphor-coated screen. When the electrons strike the phosphor-coated screen, they cause the phosphor to emit light, producing the visual image that we see on the television screen.

Que (160): If the Kinetic Energy of a body is increased by 300%, how much will its momentum increase?
A. m * v
B. 2 * m * v
C. 0.5 * m * v^2
D. None of the above

Ans: C. 0.5 * m * v^2,

The formula for kinetic energy (KE) is:

KE = 0.5 * m * v^2

where: KE = Kinetic Energy (in joules) m = Mass of the object (in kilograms) v = Velocity of the object (in meters per second).

Que (161): What type of magnetic material retains its magnetic properties even after the external magnetic field is removed?
a) Paramagnetic material
b) Diamagnetic material
c) Ferromagnetic material
d) Antiferromagnetic material

Ans: c) Ferromagnetic material,

Ferromagnetic materials are characterized by having strong magnetic properties, which means they can form permanent magnets. When a ferromagnetic material is exposed to an external magnetic field, its magnetic domains (small regions with aligned magnetic moments) tend to align with the applied field, creating a net macroscopic magnetic moment. This alignment persists even after the external magnetic field is removed.

Que (162): A fan produces a feeling of comfort during hot weather. Why?
A. Our perspiration evaporates rapidly
B. The speed of the wind is faster
C. It starts to feel airier
D. The rate of evaporation rises

Ans: Our perspiration evaporates rapidly,

When air blows over our skin, it accelerates the evaporation of moisture (sweat) from our skin. Evaporation is an endothermic process, meaning it absorbs heat from the surroundings to convert liquid water (sweat) into water vapor. As the sweat evaporates from our skin, it takes away some of the heat energy, resulting in a cooling sensation on the skin. This process helps to lower our body temperature, making us feel more comfortable in hot weather.

Que (163): Why is the gas thermometers is more sensitive than the liquid thermometer?
A. Expand more than liquids
B. Expand more than solids
C. Expand more than gases
D. Does not expand at all

Ans: Expand more than liquids,

Gases have a higher coefficient of expansion compared to liquids. When the temperature of a gas increases, the gas molecules gain kinetic energy and move more vigorously, causing them to collide with the walls of the container more frequently and with higher force.

This results in an increase in the volume of the gas as the gas molecules push against the container walls. Conversely, when the temperature decreases, the gas molecules lose kinetic energy, and the gas contracts, reducing its volume. This significant expansion and contraction of the gas with temperature changes make gas thermometers more sensitive to small temperature variations.

Que (164): Which is the correct device for the detection of thermal radiation?
A. Geiger counter
B. Geiger–Muller
C. Thermopile
D. none of these

Ans: Thermopile,

Thermopiles are often used for the detection of thermal radiation, especially in non-contact temperature measurement applications. A thermopile is a sensor that consists of multiple thermocouples connected in series or parallel. When exposed to thermal radiation (infrared radiation) from an object, the hot junctions of the thermocouples generate a voltage proportional to the temperature difference between the object and the thermopile’s cold junction.

This voltage can be measured and converted into a temperature reading using appropriate electronic circuits. In this way, thermopiles can accurately measure the temperature of objects without direct contact, making them suitable for applications like non-contact infrared thermometers, thermal imaging cameras, and various other heat sensing and temperature monitoring applications.

Que (165): The pressure at the bottom of a liquid tank does not depend on which area?
A. Area of the liquid surface
B. Area of the cylinder
C. Area of the surface tension
D. all of these

Ans: Area of the liquid surface,

The pressure at the bottom of a liquid in a closed container is determined by two factors i.e. height of the liquid column and density of the liquid.

Que (166): With the rise of temperature, what happens to the surface tension of a liquid?
A. Increases
B. Decreases
C. Constant
D. none of this

Ans: Decreases,

When the temperature of a liquid increases, the average kinetic energy of liquid molecules also increases. As a result, the intermolecular forces that create surface tension weaken. The molecules become more energetic and gain sufficient kinetic energy to overcome the cohesive forces, reducing the surface tension.

Que (167): Total internal reflection can take place when light travels from which thing?
A. Diamond to glass
B. Glass to diamond
C. Diamond to water
D. All of the above

Ans: Diamond to glass,

Total internal reflection can take place when light travels from a denser medium to a less dense medium.

Que (168): The refractive index of a given piece of transparent quartz is greatest for which light?
A. Red light
B. Yellow light
C. Violet light
D. Green light

Ans: Violet light,

In the case of transparent quartz, the refractive index is highest for violet light, which has the shortest wavelength among visible light colors. As the wavelength of light increases from violet to red, the refractive index of quartz gradually decreases.

A. Ionospheric wave
B. Visible light rays
C. EM Spectrum
D. Gamma rays

Ans: Ionospheric wave.

Que (170): Recoil of a gun is an example of which thing?
A. Conservation of linear momentum
B. Conservation of frictional movement
C. Conservation of gravity
D. none of these

Ans: Conservation of linear momentum,

The recoil of a gun is an example of Newton’s Third Law of Motion, which states: “For every action, there is an equal and opposite reaction.”

When a gun is fired, the ignited propellant in the bullet casing rapidly expands, creating high-pressure gases. These gases exert a force on the bullet, propelling it forward out of the gun barrel. However, according to Newton’s Third Law, the bullet’s acceleration forward is also accompanied by an equal but opposite force acting backward on the gun itself.

As a result, the gun experiences a recoil, which is the backward movement or kick that the gun exhibits when the bullet is fired.

Que (171): The tendency of liquid drop to contract and occupy minimum area?
A. Due to Surface tension
B. Due to Gravity tension
C. Due to frictional tension
D. Due to the surface area

Ans: Due to Surface tension,

Surface tension is a property of liquids that causes their surfaces to behave like a stretched elastic membrane. It arises from the cohesive forces between molecules at the surface of the liquid.

Que (172): When water is heated from 0 degree C to 20 degree C, how does its volume change?
A. Decreases till 4deg and then increases again
B. Decreases till 3deg and then increases again
C. Decreases till 6deg and then increases again
D. Decreases till 9deg and then increases again

Ans: Decreases till 4 deg and then increases again,

Unlike most substances, water has a peculiar behavior when its temperature changes within a specific temperature range. Between 0 degrees Celsius and 4 degrees Celsius, the volume of water actually decreases as its temperature rises. This is because water is most dense at approximately 4 degrees Celsius. As it cools below this temperature, it expands due to the formation of ice (which is less dense than liquid water).

However, once water’s temperature rises above 4 degrees Celsius, it behaves more conventionally, and its volume increases with temperature.

Que (173): If the angle between two plane mirrors is 60°; then how many number of image will be formed?
A. 3
B. 7
C. 5
D. 1

Ans: 3,

The number of images formed by multiple reflections between two mirrors can be calculated using the formula:

Number of images = (360 degrees) / (angle between mirrors – 180 degrees)

In this case, the angle between the mirrors is 60 degrees:

Number of images = (360 degrees) / (60 degrees – 180 degrees)

Number of images = (360 degrees) / (-120 degrees)

Number of images = -3

The result is -3, which means that three images will be formed.

Que (174): With which can Radio wave of constant amplitude be generated?
A. Diode
B. Transmitter
C. Oscillator
D. none of these

Ans: Oscillator,

An oscillator is a circuit that produces a continuous and stable oscillating waveform, typically at a specific frequency. In the context of radio wave generation, an oscillator can generate a continuous and constant amplitude radio wave at a specific frequency.

Que (175): Which element is with the highest electrical conductivity?
A. Gold
B. Silver
C. Copper
D. Bronze

Ans: Silver.