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Practice Set For SI Units

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SI unit is considered as an International System of units from 1960. Having a standard unit system it helps the entire world to understand the measurements in one set of units. We know about two types of SI units, one is base SI units and another is derived SI units. SI units play an important role in various competitive exams like UPSC, CDS, SSC CGL, Air force and other government exams.

PRACTICE QUESTIONS ON SI UNITS ASKED IN SSC CGL EXAMS:

Q.1 What is the SI unit of the Surface tension?
a) Nm
b) N/m
c) N/m2
d) Nm2
Ans: b) N/m
Explanation:
Surface Tension is the force required to keep a unit length of a film of fluid in equilibrium.
It is dimensionally equal to the ratio of force and length.
Surface Tension (S)= F/L
As SI unit of Force is Newton and the SI unit of length is meter.
Hence SI unit of Surface Tension is Newton per meter (N/m).

Q.2 What is the SI unit of Electric Field?
a) Nm C
b) Nm C-1
c) N C-1
d) NC-2
Ans: c) N C-1
Explanation:
Electric Force per unit Charge measures Electric Field.
Hence Electric Field (E) = (Electric Force(F))/(Charge(Q))
As SI unit of Force is Newton and the SI unit of Charge is Coulomb.
Therefore, 
the SI unit of the Electric Field in Newton per Coulomb (NC-1).

Q.3 What is the SI base unit of Impulse?
a) kg m
b) kg m2s
c) kg m/s
d) kg m/s2
Ans: c) kg m/s
Explanation:
According to the Impulse momentum theorem, the Impulse applied to an object will be equal to the change in its momentum.
Thus  Impulse = change in momentum
Again momentum = mass  × velocity
As SI base unit of mass is kg and SI base unit of velocity is m/s
Hence SI base unit of Impulse is kg m/s.

Q.4 What is the SI base unit of Force?
a) kg m
b) kg m2s
c) kg m/s
d) kg m/s2
Ans: d) kg m/s2
Explanation:
According to the formula of Force, 
Force(F)= Mass(m) × Acceleration(a)
As the SI unit of Mass is kg and the SI unit of Acceleration is m/s2
Thus SI base unit of Force is kg m/s2

Q.5 What is the SI unit of Pressure? 
a) Ampere
b) volt
c) Pascal
d) Ohm
Ans: c) Pascal
Explanation:
Pressure is defined as Force per unit area.
And its SI unit is Pascal.
The unit is named after Blaise Pascal
Pascal = Newton per square meter.

Q.6  What is the SI unit of Heat?
a) Kelvin
b) Joule
c) calorie
d) Erg
Ans: b) Joule
Explanation:
As Heat is a form of energy and we know that unit of energy is always equal to the Unit of Work.
As SI unit of Work is the joule.
Thus SI unit of heat is Joule.

Q.7  What is the SI unit of Specific Heat Capacity?
a) J kg k
b) J kg k-1
c) J kg-1 k-1
d) J kg k-2
Ans: c) J kg-1 k-1
Explanation:
We know the Formula of Heat –
            H= m s ∆t
Where m =mass 
             S=Specific heat
            ∆t=Change in temperature
Thus Formula of Specific heat Capacity, S=H/m ∆t
As the SI unit of Heat(H) is Joule
SI unit of Mass(m) is Kg
SI unit of temperature(∆t) is Kelvin.
Hence SI unit of Specific Heat Capacity is Joule per Kilogram per Kelvin (J kg-1 k-1).

Q.8 What is the SI unit of Coefficient of Viscosity?
a) N s m
b) N s m2
c) N s m-2
d) N s m-1
Ans: c) N s m-2   i.e Newton Second Per Square meter.
Explanation:
The coefficient of Viscosity is a measure of resistance to the flow of the fluid.
We know the formula of Viscous Force, F = µA. ∆v⁄∆x
Where A is the Surface area 
              µ is the Coefficient of Viscosity.
              ∆v/∆x is the Velocity gradient.
Thus µ = F/A×(∆x/∆v)
Hence SI unit of µ = (Newton/m2) × (m/(m/s))
                                = (Newton second)/(Square meter)
Therefore, 
SI unit of Viscosity is Newton Second Per Square meter (N S m-2) .

Q.9  What is the SI unit of Electric Flux?
a)  N m2 C-1
b)   N m C-1
c)   N m C
d)   N m2 C
Ans: a) N m2C-1
Explanation:
Electric Flux is the number of electric field lines passing through a given surface area.
Electric Flux  = Electric Field × Area of given Surface
Again Electric Field is equal to electric force per unit charge.
SI unit of Electric Field is Newton Per Coulomb.
SI unit of Surface Area is a Square meter.
Thus 
SI unit of Electric Flux is Newton Square meter Per Coulomb (N m2 C-1).

Q.10  What is the SI unit of Inductance?
a) Tesla
b) Weber
c) Curie
d) Henry
Ans: d) Henry 
Explanation:
Inductance is the property of an electric conductor that causes an electromotive force to be generated by a change in the current flowing.
SI unit of Inductance is Henry. It is also known as Weber per Ampere.

Q.11  What is the SI unit of Magnetic Flux?
a) Siemens 
b) Tesla
c) Weber
d) Henry
Ans: c) Weber.
Explanation:
Magnetic Flux (Ø)= The number of magnetic field lines passing a surface area is called Magnetic Flux.
Ø = B.A
Where B is the Magnetic field
      And  A is the Surface area.
SI unit of the Magnetic Flux is Weber.

Q.12  Coulomb is the equivalent of which SI unit?
a) Ampere second
b) Ampere volt
c) Ampere ohm
d) Ampere watt
Ans: a) Ampere second
Explanation:
As Coulomb is the SI unit of the charge.
And Charge = Current × Time
As SI unit of Current in Ampere
And a unit of Time is Second.
Hence Coulomb = Ampere × Second.

Q.13 SI unit of Electric Resistance is equivalent to—?
a) Volt meter
b) Volt Ampere
c) Volt / Ampere
d) Watt
Ans: c) Volt /Ampere
Explanation:
SI unit of Electric Resistance is Ohm.
And Ohm is equivalent to Volt/Ampere.
As we know the relation between the Electric Resistance(R), Electric Current(I) and Potential Difference(V) is
V= IR
=>R=V/I
As SI unit of Potential Difference(V) is Volt.
And SI unit of Electric Current (I) is Ampere.
Hence SI unit of R= Volt/Ampere.

Q.14  Watt is the equivalent of which SI unit?
a) Volt
b) Volt meter
c) Ampere Volt
d) Ampere meter
Ans: c) Ampere Volt.
Explanation:
Watt is the SI unit of Power
In Electricity, P=IV
Where I is Electric current
            V is the Potential Difference of the Circuit.
As SI unit of I is Ampere
And SI unit of V is Volt.
Hence, Watt = Ampere × Volt.

Q.15  What is the SI unit of Solid angle?
a) Radian
b) Radian /Second
c) Steradian
d) Degree.
Ans: c) Steradian
Explanation:
Steradian is the SI unit of Solid angle.
Radian is the SI unit of Plane angle.
Radian/second is the SI unit of Angle Velocity.

Q.16 What is the SI base unit of Work?
a)  m2kg s-2
b)  m kg s-1
c)  m kg
d)  m2 kg s
Ans: a) m2 kg s-2
Explanation:
As Work = Force(F)×Displacement (S)
And Force(F) = Mass(m) × Acceleration(a)
SI unit of Mass is Kg and SI unit of Acceleration is m/s2
Thus SI unit of Force is Kg m/s2
Again SI unit of Displacement is meter(m)
Hence SI base unit of Work = (kg m/s2)×m = m2kg s-2.

Q.17  What is the SI unit of Luminous Flux?
a) Lux
b) Lumen
c) Candela
d) Parsec
Ans: b) Lumen
Explanation:
Lumen is the SI unit of Luminous Flux.
Lux is the SI unit of Intensity of Illumination.
Candela is the SI unit of Luminous Intensity.
Parsec is the unit of Distance to Stars and Galaxies.

Q.18  What is the SI unit of the Electric Potential Difference?
a) Volt
b) Ohm
c) Amp
d) Watt
Ans: a) Volt
Explanation:
Volt is the SI unit of Electric Potential Difference.
Ohm is the unit of Electric Resistance.
Amp is the unit of Current Electricity.
Watt is the unit of Power.

Q.19  SI unit of Power is equivalent to…..?
a) Joule
b) Joule/sec
c) Kelvin
d) Kelvin/sec
Ans: b) Joule/sec
Explanation:
Power is the rate of doing work. It is equivalent to the amount of energy consumed per unit of time.
Power(P)=Work/Time
As SI unit of Work is Joule and unit of time is Second.
Hence SI unit of Power is  Joule/sec.

Q.20  SI unit of Electric Conductance is…?
a) Siemens
b) Henry
c) Tesla
d) Joule
Ans: a) Siemens
Explanation:
Siemens is the SI unit of Electric Conductance.
Henry is the SI unit of Inductance.
Tesla is the SI unit of Magnetic Field, Magnetic flux density, and Magnetic Induction.
Joule is the SI unit of Work and all forms of Energy.
 



Last Updated : 06 Dec, 2022
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