1. In the following which is fundamental physical quantity?
(a) Force
(b) Velocity
(c) Electric current
(d) Work
(e) None of the above/More than one of the above
[66th B.P.S.C. (Pre) (Re. Exam) 2020]
Ans. (c) Electric current
- In physics, there are seven basic physical measurements (which are measured using basic units): length, mass, time, electric current, temperature, light intensity, and amount of something.
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2. The unit of power is –
(a) Hertz
(b) Volts
(c) Watt
(d) Neutron
[U.P.P.S.C. (GIC) 2010]
Ans. (c) Watt
- Power is a measure of how fast energy is being used or transferred.
- It is calculated by dividing the amount of work done (in joules) by the time it takes to do the work (in seconds).
- The basic unit of power is the watt, which is equal to one joule per second.
- Power is usually written as watts (W) or kilowatts (KW).
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3. The unit of electric power is :
(a) Ampere
(b) Volt
(c) Coulomb
(d) Watt
(e) None of the above / More than one of the above
[65th B.P.S.C. (Pre) 2019, 64th B.P.C.S. (Pre) 2018]
Ans. (d) Watt
- Electric power is how quickly electrical energy moves through a circuit.
- Its unit in the SI system is called the watt.
- Ampere is the unit of electric current, voltage is the unit of electrical potential and coulomb is the unit of electric charge.
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4. The unit of the force is –
(a) Faraday
(b) Fermi
(c) Newton
(d) Rutherford
[M.P.P.C.S. (Pre) 1990]
Ans. (c) Newton
- Force is a physical concept that causes something to move.
- The measurement of force is in Newtons (or kg.m/sec²).
- This is based on Isaac Newton’s law which states that force is equal to the mass of an object multiplied by its acceleration.
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5. The unit of work is :
(a) Joule
(b) Neutron
(c) Watt
(d) Dyne
[U.P.P.C.S. (Pre) 1996]
Ans. (a) Joule
- When a force causes something to move, the work done is equal to the amount of force multiplied by how far the object moves in the direction of the force.
- This is a number without direction.
- The unit used to measure work is the Newton metre, which is also known as a joule.
- The joule is also the unit of energy.
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6. Frequency is measured in
(a) hertz
(b) metre/second
(c) radian
(d) watt
(e) None of the above / More than one of the above
[64th B.P. S.C. (Pre) 2018]
Ans. (a) hertz
- The Hertz, which is represented by the symbol Hz, is a unit of measurement for frequency used in the International System of Units (SI system).
- It is equal to one cycle per second.
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*9. ‘Ohm-meter’ is a unit of :
(a) Resistance
(b) Conductance
(c) Resistivity
(d) Charge
(e) None of the above/More than one of the above
[66th B.P.S.C. (Pre) (Re. Exam) 2020]
Ans. (c) Resistivity
- The ohm-meter (ohm-m) is a measure of resistivity, which is the ability of a material to resist the flow of electricity.
- The standard unit of electrical resistivity is the ohm-meter, represented by the symbol ⍴.
- Faraday is the unit for capacitance, volt is the unit for electric potential, ampere is the unit for electric current and ohm is the unit for electrical resistance (not resistivity).
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11. A light-year is the –
(a) Year which had maximum sunlight
(b) Year in which workload was very light
(c) Distance travelled by light in one year
(d) Mean distance between Sun and Earth
[U.P. Lower Sub. (Mains) 2013]
Ans. (c) Distance travelled by light in one year
- A light-year is the distance that light can cover in a single year.
- Light moves at a rate of 186,000 miles per second or 5.88 trillion miles in a year.
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14. Which one of the following is a reason why astronomical distances are measured in light-years?
(a) Distances among stellar bodies do not change
(b) Gravity of stellar bodies does not change
(c) Light always travels in straight line
(d) Speed of light is always same
[I.A.S. (Pre) 2021]
Ans. (d) Speed of light is always same
- A light-year is the amount of space a beam of light can travel in one year on Earth.
- Light travels at a constant speed in a vacuum, which is an area without any gravity.
- This speed is the same throughout the universe and is very accurately known.
- That is why astronomers use light-years to measure distances in space.
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*15. A parsec, a unit of distance used to measure the distance related to the stars in the sky, is equal to –
(a) 4.25 light-years
(b) 3.25 light-years
(c) 4.50 light-years
(d) 3.05 light-years
[R.A.S./R.T.S. (Pre) 1999]
Ans. (b) 3.25 light-years
- A parsec is a unit of length that is utilized to quantify the vast distances of celestial objects located outside of our solar system.
- It is a combination of the words “parallax” and “arcsecond”.
- It is equal to approximately 3.08 × 1016 meters. In comparison, a light-year is equivalent to about 9.46 × 1015 meters.
- Therefore, 1 parsec is approximately equal to 3.256 light-years. Based on the given options, only option (b) is in close proximity to the accurate answer.
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17. Which unit of measurement is multiplied by 0.39 to convert it to ‘inches’?
(a) Millimetre
(b) Centimetre
(c) Metre
(d) Decimetre
[U.P. U.D.A./L.D.A. (Pre) 2010]
Ans. (b) Centimetre
- 1 cm is equal to 0.39 inches, so to change cm to inches, we need to multiply it by 0.39.
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18. How can the height of a person who is six feet tall, be expressed (approximately) in nanometre?
(a) 183 × 106 nm
(b) 234 ×106 nm
(c) 183 × 107 nm
(d) 181 × 107n m
[I.A.S. (Pre) 2008]
Ans. (c) 183 × 107nm
- One nanometer is equivalent to 10^-9 meters.
- One foot is equal to 0.305 meters.
- One foot is equal to 30.5 × 10^7 nanometers.
- Thus, 6 feet is equal to 6 × 30.5 × 10^7 nanometers, which is equal to 183 × 10^7 nanometers.
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19. A nanometre is equal to –
(a) 10-6 cm
(b) 10–7 cm
(c) 10-8 cm
(d) 10-9 cm
[U.P. U.D.A./L.D.A. (Pre) 2013]
Ans. (b) 10–7 cm
- One nanometer is equal to 1.0 × 10^-9 meters.
- Since 1 meter is equivalent to 100 centimeters, then 10^-9 meter is equal to 10^2 × 10^-9 centimeters, which simplifies to 10^-7 centimeters.
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20. Ampere is the unit of –
(a) Voltage
(b) Electric current
(c) Resistance
(d) Power
[Chhattisgarh P.C.S. (Pre) 2005]
Ans. (b) Electric current
- Ampere is the way we measure electric current. If there is one ampere of current going through a wire, it means that 6.25 x 1018 electrons are flowing in each direction each second.
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21. Megawatt is the measuring unit of power which is –
(a) Generated
(b) Consumed
(c) Saved
(d) Lost in transmission
[U.P. Lower Sub. (Pre) 1998]
Ans. (a) Generated
- A megawatt is a unit of power that is produced by power plants and power stations.
- One megawatt is equal to 1 million watts.
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22. Match List-I with List-II and select the correct answer from the code given below :
| List-I |
List-II |
| (Physical quantities) |
(Units) |
| A. Acceleration |
1. Joule |
| B. Force |
2. Newton second |
| C. Work done |
3. Newton |
| D. Impulse |
4. Metre/second² |
Code :
A B C D
(a) 1 2 3 4
(b) 3 4 1 2
(c) 2 3 4 1
(d) 4 3 1 2
[U.P.P.C.S. (Pre) 2005, U.P. U.D.A./L.D.A. (Pre) 2001]
Ans. (d) 4 3 1 2
- Acceleration describes how quickly something is speeding up or slowing down, measured over a period of time.
- The standard unit for acceleration is metres per second squared (m/s²).
- The standard unit for force is newtons (N), the standard unit for impulse is newton seconds (Ns), and the standard unit for work is joules (J).
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*23. Which one of the following SI units is not correctly matched?
(a) Work – Joule
(b) Force – Newton
(c) Mass – kg.
(d) Pressure – Dyne
[U.P. Lower Sub. (Pre) 2013]
Ans. (d) Pressure – Dyne
- Pascal is a unit of pressure or stress that is used in the International System of Units.
- Dyne is a unit of force that is used in the CGS system.
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24. Match List-I with List-II and select the correct answer using codes given below :
| List-I |
List-II |
| (Units) |
(Parametric quantities) |
| A. Watt |
1. Heat |
| B. Knot |
2. Navigation |
| C. Nautical mile |
3. Speed of a ship |
| D. Calorie |
4. Power |
Code :
A B C D
(a) 3 1 4 2
(b) 1 2 3 4
(c) 4 3 2 1
(d) 2 4 1 3
[U.P. U.D.A./L.D.A. (Pre) 2002]
Ans. (c) 4 3 2 1
- The watt (W) is the standard unit of power, which equals one joule per second.
- The knot is used to measure the speed of a ship.
- Navigators use the nautical mile to measure distance.
- The calorie is the unit to measure heat and energy.
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25. Match the following :
| A. Joule |
1. Current |
| B. Ampere |
2. Power |
| C. Watt |
3. Work |
| D. Volt |
4. Electric potential |
Code :
A B C D
(a) 3 1 2 4
(b) 1 2 3 4
(c) 4 3 2 1
(d) 1 3 2 4
[U.P.P.C.S. (Pre) 1990]
Ans. (a) 3 1 2 4
- Joule is the measure of work used in the metric system.
- Ampere, watt and volt are the measurements of current, power and electrical potential.
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*26. How many watts are there in a horsepower?
(a) 1000
(b 750
(c) 746
(d) 748
[M.P.P.C.S. (Pre) 1991]
Ans. (c) 746
- Horsepower is a way to quantify the amount of work being done.
- One watt is equal to one joule per second and one horsepower is equal to 746 watts.
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27. Which one of the following is not correctly matched?
(a) Knot – Measure of speed of ship
(b) Nautical mile – Unit of distance used in navigation
(c) Angstrom – Unit of wavelength of light
(d) Light year – Unit of measuring time
[U.P.P.C.S. (Mains) 2010]
Ans. (d) Light year – Unit of measuring time
- A light year is not a way to measure time, but a way to measure distance.
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*28. Angstrom is a unit of
(a) wavelength
(b) energy
(c) frequency
(d) velocity
(e) None of the above / More than one of the above
[64th B.P.C.S. (Pre) 2018]
Ans. (a) wavelength
- The Angstrom is a unit of length, usually used to measure the wavelength of light.
- It’s equal to 0.1 nanometres or 10-10 metres.
- It was named after a 19th century Swedish physicist, Anders Jonas Angstrom.
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*29. Match List-I (Quantity) with List-II (Units) and select the correct answer using the codes given below the lists:
| List I |
List II |
| A. High speed |
1. Mach |
| B. Wavelength |
2. Angstrom |
| C. Pressure |
3. Pascal |
| D. Energy |
4. Joule |
Code :
A B C D
(a) 2 1 3 4
(b) 1 2 4 3
(c) 1 2 3 4
(d) 2 1 4 3
[U.P.P.C.S. (Pre) 2006, I.A.S. (Pre) 1999]
Ans. (c) 1 2 3 4
- The Mach number is a way to compare the speed of something to the speed of sound.
- If an object is going faster than the speed of sound, it is said to be travelling at supersonic speed (Mach 1).
- Mach is a measure of high speed. Wavelength is measured in angstroms, pressure in pascals, and energy in joules.
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30. ‘Joule’ is related to energy in the same way as ‘Pascal’ is related to :
(a) Mass
(b) Pressure
(c) Density
(d) Purity
(e) None of the above
[Chhattisgarh P.C.S. (Pre) 2015]
Ans. (b) Pressure
- Joule is a measure of energy in the International System of Units (SI), and Pascal is the measure of pressure in the SI.
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*32. One micron represents a length of –
(a) 10-6 cm
(b) 10-4 cm
(c) 1 mm
(d) 1 m
[U.P.P.C.S. (Mains) 2011]
Ans. (b) 10-4 cm
- A micron signifies a measurement of 10^-6 meters and is denoted by the symbol “µ.”
- This is equivalent to 0.000001 meters or 0.0001 centimeters.
- In other words, it can be expressed as 1/1000 or 1/10^4 centimeters, which simplifies to 10^-4 centimeters.
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*33. Which one of the following is not correctly matched?
(a) Decibel – Unit of sound intensity
(b) Horsepower – Unit of power
(c) Nautical miles – Unit of naval distance
(d) Celsius – Unit of heat
[U.P.P.C.S. (Spl.) (Mains) 2004, U.P.P.C.S.(Pre) 2001]
Ans. (d) Celsius – Unit of heat
- Celsius is a way to measure temperature. Calories measure heat.
- A nautical mile is a unit of distance that is equal to 1.852 kilometers.
- The SI unit of power is the watt, which is the same as a Joule per second.
- Horsepower and metric horsepower are also units of power and 1 horsepower is equal to 746 watts.
- Decibel is used to measure sound intensity.
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34. Which one of the following is not the unit of heat?
(a) Calorie
(b) Kilocalorie
(c) Kilojoule
(d) Watt
[M.P. P.C.S. (Pre) 2016]
Ans. (d) Watt
- The watt is a type of measurement for power that comes from the International System of Units.
- All other measurements are for heat.
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*35. Which one of the following is not the unit of heat?
(a) Centigrade
(b) Calorie
(c) Erg
(d) Joule
[U.P. R.O./A.R.O. (Pre) 2017]
Ans. (a) Centigrade
- Temperature is how hot or cold something is.
- We measure it using a thermometer that is marked according to a temperature scale like Centrigrade, Fahrenheit or Kelvin.
- Heat energy is measured using the calorie, erg and joule.
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36. A distance of 1 km. means –
(a) 100 m.
(b) 1000 cm.
(c) 1000 m.
(d) 100 cm.
[45th B.P.S.C. (Pre) 2001]
Ans. (c) 1000 m.
- Distance is measured in metres. One kilometre is the same as 1000 metres.
- One metre is the same as 100 centimetres.
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*37. One pikogram is equal to –
(a) 10–6 gram
(b) 10–9 gram
(c) 10–12 gram
(d) 10–15 gram
[42nd B.P.S.C. (Pre) 1997]
Ans. (c) 10–12 gram
- Mass is measured in small units called Milligrams (10-3 grams), Micrograms (10-6 grams), Pikograms (10-12 grams) and Femtograms (10-15 grams).
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39. What is the unit of pressure?
(a) Newton / sq. metre
(b) Newton-metre
(c) Newton
(d) Newton/metre
(e) None of the above / More than one of the above
[64th B.P.C.S. (Pre) 2018]
Ans. (a) Newton / sq. metre
- The unit of measure for pressure is called pascal (Pa) and it is the same as one newton per square metre (N/m² or kg m-1s-2).
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*40. The unit of pressure is
(a) kg/cm²
(b) kg/cm
(c) kg/mm
(d) kg/cm³
(e) None of the above/More than one of the above
[65th B.P.S.C. (Pre) 2019]
Ans. (e) None of the above/More than one of the above
- The kilogram-force per square centimeter (kgf/cm²) is a pressure unit that is considered deprecated.
- It was commonly written as kilogram per square centimeter (kg/cm²), which is an incorrect expression for pressure.
- The correct representation should be kgf/cm².
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*41. What is the unit of atmospheric pressure?
(a) Bar
(b) Knot
(c) Joule
(d) Ohm
[Chhattisgarh P.C.S. (Pre) 2008]
Ans. (a) Bar
- The bar is a metric unit of pressure, although it is not part of the International System of Units (SI).
- It is defined as equal to 105 newtons per square meter.
- In contrast, the pascal is the SI unit of pressure.
- To clarify, 1 bar is equivalent to 105 pascals.
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*42. 1 kg/cm² pressure is equivalent to :
(a) 0.1 bar
(b) 1.0 bar
(c) 10.0 bar
(d) 100.0 bar
[Uttarakhand P.C.S. (Pre) 2002]
Ans. (b) 1.0 bar
- In this question, the term 1 kg/cm² is used to represent 1 kilogram-force per square centimeter (kgf/cm²).
- It is worth noting that 1 dyne is equivalent to 1.02 × 10^-6 kilogram-force (kgf). Additionally, 1 bar is equal to 10^6 dyne per square centimeter (dyne/cm²).
- Therefore, by substituting the value of dyne into the value of bar, we can determine that: 1 bar is equal to 10^6 dyne/cm², which is equivalent to 1.02 × 10^-6 × 10^6 kgf/cm².Hence, 1 bar is approximately equal to 1.02 kgf/cm².
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43. Which one of the following quantities does not have unit?
(a) Stress
(b) Force
(c) Strain
(d) Pressure
(e) None of the above/More than one of the above
[65th B.P.S.C. (Pre) 2019]
Ans. (c) Strain
- Whenever an outside force changes the shape or size of an object, it is called strain.
- Since it is a ratio, it doesn’t have any units.
- Force is measured in newtons (kg m/s2) and stress and pressure are measured in pascals (kg m-1 s-2).
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*44. 1 barrel of oil is equal to which of the following?
(a) 131 litre
(b) 159 litre
(c) 179 litre
(d) 201 litre
[U.P.P.C.S. (Pre) 2009]
Ans. (b) 159 litre
- The amount of oil is now measured in cubic metres.
- 1 barrel = 158.9873 litre
- 1 barrel = 0.158987 cubic metre
- 1 barrel = 42 U.S. gallon
- 1 barrel = 34.9723 U.K. gallons.
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*45. The smallest unit of length is –
(a) Micron
(b) Nanometre
(c) Angstrom
(d) Fermimetre
[U.P.P.C.S. (Pre) 2005]
Ans. (d) Fermimetre
- Here are the rephrased statements:
- A micron is equal to 10^-6 meters.
- A nanometer is equal to 10^-9 meters.
- An angstrom is equal to 10^-10 meters.
- A fermi (femtometer) is equal to 10^-15 meters.
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*46. Match List-I with List-II and select the correct answer using the codes given below the lists.
| List – I |
List – II |
| A. Cusec |
1. Pressure |
| B. Byte |
2. Intensity of Earthquake |
| C. Richter |
3. Rate of flow |
| D. Bar |
4. Computer |
Code :
A B C D
(a) 1 2 3 4
(b) 3 4 2 1
(c) 4 3 2 1
(d) 3 4 1 2
[U.P. Lower Sub. (Spl.) (Pre) 2008]
Ans. (b) 3 4 2 1
- Cusec stands for cubic feet per second and is a way to measure how much water is flowing – it’s 28.317 litres per second.
- A byte is a unit of digital information which has 8 bits.
- The Richter magnitude scale is a way to work out the energy released by an earthquake.
- The bar is a metric unit of pressure and it is exactly the same as 100,000 Pascal.
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47. What is measured in cusec?
(a) Purity of water
(b) Depth of water
(c) Flow of water
(d) Quantity of water
[Uttarakhand P.C.S. (Pre) 2006]
Ans. (c) Flow of water
- The irrigation department often uses Cusec to tell how much water is released from reservoirs.
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48. Which one of the following is the unit of measure of the thickness of the ozone layer of the atmosphere?
(a) Knot
(b) Dobson
(c) Poise
(d) Maxwell
[Uttarakhand P.C.S. (Pre) 2010]
Ans. (b) Dobson
- The thickness of the ozone layer is measured with a unit called Dobson unit, which is the same as 0.01 mm in the Earth’s atmosphere at normal temperature and pressure.
- This unit was named after G.M.B. Dobson, who studied ozone in the atmosphere.
- One Dobson unit is equal to 2.687 x 1020 molecules of ozone per square meter.
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Key Facts for Revision
- 1 inch = 2.54 cm
- 1 ft = 12 inch
- Dyne is a unit of force that is used in the CGS system.
- The knot is used to measure the speed of a ship.
- 1 horsepower is equal to 746 watts.
- The Angstrom is a unit of length, usually used to measure the wavelength of light.
- The Mach number is a way to compare the speed of something to the speed of sound.
- One micron is equal to 10-6 meters
- Heat energy is measured using the calorie, erg and joule.
- Mass is measured in small units called Milligrams (10-3 grams), Micrograms (10-6 grams), Pikograms (10-12 grams) and Femtograms (10-15 grams).
- The bar is a metric unit of pressure, although it is not part of the International System of Units (SI). It is defined as equal to 105 newtons per square meter. To clarify, 1 bar is equivalent to 105 pascals. 1 kg/cm² pressure is equivalent to 1 bar.
- Strain is unitless.
- 1 barrel = 159 litre
- 1 litre = 0.oo1 cubic metre
- 1 barrel = 42 U.S. gallon
- 1 barrel = 35 U.K. gallon
- A micron is equal to 10^-6 meters.
- A nanometer is equal to 10^-9 meters.
- An angstrom is equal to 10^-10 meters.
- A fermi (femtometer) is equal to 10^-15 meters.
- Cusec stands for cubic feet per second and is a way to measure how much water is flowing (28.317 litres per second)
- Dobson unit, which is the same as 0.01 mm thickness of ozone layer.
