25 questions on “Physics GK Mock Test” objective questions series – first law of thermodynamics, seismic waves, paramagnetic material, tyndall effect, soap bubble, rectifier circuit, frequency, centrifugal force, mercury, uniform magnetic field, S. Chandrashekhar, brightest planet, watery planet, ray of light frequency, barometric reading, relative humidity, green house effect, power of lens, mirrors, gamma rays, infrared rays, absolute humidity etc.

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 (76): The first law of thermodynamics is concerned with the conservation of which thing?
A. Velocity
B. Gravity
C. Speed
D. Energy

A simple formulation is: “The total energy in a system remains constant, although it may be converted from one form to another.” Another common phrasing is that “energy can neither be created nor destroyed”.

Que (77): What is the proper order of seismic waves as they are received at seismograph station?
A. P > S > L
B. S > P > L
C. L > S > P
D. None of the above

Answer: A. P-wave > S-wave > L-wave,
P-wave is the primary and is the fastest among all.

Que (78): What is the relative permeability of a paramagnetic material?
A. Greater than unity
B. Lesser than unity
C. Equal to unity
D. Depends on various factors

Answer: A. Greater than unity,
For diamagnetic material it is less than 1, Paramagnetic substances are weakly attracted by the magnetic field when placed in an external magnetic field and hence for it the relative permeability is greater than unity.

Que (79): In Tyndall effect ________ wavelengths are transmitted more.
A. Longer
B. Shorter
C. Both
D. None

Longer wavelengths are transmitted more and shorter ones scatters more.

Que (80): If a soap bubble is given negative charge then what happen to its radius?
A. Increases
B. Decreases
C. Stays the same
D. None of these

The negative charge will distribute itself evenly over the surface of the bubble, and repulsion will happen as like charges repel each other hence it will expand.

Que (81): Which electrical circuit is used to get smooth DC output from a rectified circuit?
A. Parallel Circuit
B. Electric circuit
C. Open circuit
D. Rectifier circuit

Answer: D. Rectifier Circuit,
The electrical circuit used to get smooth dc output from a rectifier circuit is known as a RECTIFIER CIRCUIT. In a rectifier, a DIODE is used to get a dc current output.

Que (82): The absorption of radio waves by the atmosphere depends on:
A. Energy
B. Time
C. Frequency
D. Distance

Que (83): On planet Earth there is no centrifugal force at ____________.
A. At the center
B. At the poles
C. Where there is water
D. Where there is land

Answer: B. At the Poles.

Que (84): Which planet has the shortest year?
A. Mercury
B. Venus
C. Saturn
D. Mars

Mercury has the shorted year 88 earth days.

Que (85): How must be the The lines of force of a uniform magnetic field?
A. Parallel to each other
B. Perpendicular to each other
C. Intersecting each other
D. Following a measurement

Answer: A. Parallel to each other.

Que (86): Name of S. Chandrashekhar is associated with which subject?
A. Cosmology
B. Astrophysics
C. Astrology
D. Physics

S. Chandrashekhar was a great scientist known for Chandrashekhar limit and shared 1983 Nobel prize for Physics.

Que (87): Which is the brightest planet?
A. Mars
B. Jupiter
C. Uranus
D. Venus

Venus is always brighter than all other planets or stars as seen from Earth.

Que (88): Which planet is the watery planet?
A. Mars
B. Earth
C. Uranus
D. Venus

Que (89): When a ray of light is going from one medium to another, what will happen to its frequency?
A. Frequency increases
B. Frequency decreases
C. Frequency remains the same
D. Frequency fluctuates

Answer: C. Frequency remains the same,
When light travels from one medium to another, the speed changes, as does the wavelength but the frequency does not change.

Que (90): What happens when a sudden fall in the barometric reading occurs?
A. Tide
B. Earthquake
C. Famine
D. Storm

Barometer is used to measure the atmospheric pressure. Sudden fall indicates storm, if fall is gradual then it indicates rain.

Que (91): Heat given to an ideal gas under isothermal conditions is used in which work?
A. In doing internal work
B. In doing external work
C. Both
D. None of these

Answer: B. In doing external work.

Que (92): Relative humidity of the atmosphere is directly affected by _____
A. Rainfall
B. Change in atmospheric temperature
C. Unseasonal change
D. None of these

Answer: B. Change in atmospheric temperature.

Que (93): When will a hot body radiate maximum energy?
A. If its surface is made of metal
B. If the surface is a conductor
C. If its surface is black
D. None of these

Answer: C. If its surface is black,
Black body absorbs maximum heat and hence radiates maximum heat.

Que (94): Which will you put into pure water in order to pass electric current through it?
A. Electrode
B. Plastic
C. Salt
D. None of the above

Que (95): “Green house effect” with respect to global warming refers to which effect?
A. Air pollution
B. Toxication
C. Warming effect

The greenhouse effect is the process by which radiation from a planet’s atmosphere warms the planet’s surface to a temperature above what it would be without this atmosphere.

Que (96): Power of lens is ________ proportional to focus?
A. Directly
B. Inversely
C. Exponential
D. Cube

Que (97): How many image can a man see if he stands between two plane mirrors inclined at an angle of 60°?
A. 3
B. 4
C. 5
D. 6

Que (98): Which rays can pass through 20 cm thickness of steel?
B. X-rays
C. Infrared rays
D. Gamma rays

Answer: D. Gamma rays,
Gamma rays are of shortest wavelength and have high penetrating capacity.

Que (99): Old-written material, which cannot be read easily, can be read by using:
A. By X-rays
B. By gama rays
C. By infrared rays
D. None of these

Answer: C. By infrared rays.

Que (100): What is the quantity of water in a particular volume of air called?
A. Absolute humidity
B. No humidity at all
C. One forth humidity
D. Half the humidity