[100+] Based Quantities & Derived Quantities MCQs Class 9

In the study of physics, understanding based quantities and derived quantities is fundamental. Based quantities are those that are chosen independently, while derived quantities are calculated from base units. Mastering these concepts is essential for a solid foundation in physics. These multiple-choice questions will help reinforce your knowledge.

What is the SI unit of length?
A) Kilogram
B) Meter
C) Second
D) Ampere
Correct Option: B
Explanation: The SI unit of length is meter (m).
Which of the following is a base quantity?
A) Velocity
B) Time
C) Force
D) Energy
Correct Option: B
Explanation: Base quantities are fundamental physical quantities, and time is one of them.
What is the derived unit of speed?
A) Meter
B) Second
C) Meter per second
D) Newton
Correct Option: C
Explanation: Speed is defined as distance traveled per unit time, hence its unit is meters per second (m/s).
What is the SI unit of force?
A) Newton
B) Kilogram
C) Joule
D) Watt
Correct Option: A
Explanation: The SI unit of force is Newton (N).
Which of the following is not a derived quantity?
A) Density
B) Speed
C) Acceleration
D) Length
Correct Option: D
Explanation: Length is a base quantity, not derived from any other quantities.
If a car travels 200 meters in 20 seconds, what is its speed?
A) 10 m/s
B) 20 m/s
C) 5 m/s
D) 15 m/s
Correct Option: A
Explanation: Speed = Distance / Time = 200 m / 20 s = 10 m/s.
Which of the following is the correct equation for acceleration?
A) $a = \frac{v}{t}$
B) $a = \frac{v}{s}$
C) $a = \frac{s}{t}$
D) $a = \frac{t}{s}$
Correct Option: C
Explanation: Acceleration is the rate of change of velocity with time, so it is calculated as $a = \frac{\Delta v}{\Delta t}$ .
What is the SI unit of acceleration?
A) Meter
B) Second
C) Meter per second
D) Meter per second squared
Correct Option: D
Explanation: Acceleration is measured in meters per second squared (m/s²).
Which of the following represents a vector quantity?
A) Mass
B) Temperature
C) Distance
D) Displacement
Correct Option: D
Explanation: Displacement is a vector quantity as it has both magnitude and direction.
What is the formula for calculating displacement?
A) $s = vt$
B) $s = \frac{v}{t}$
C) $s = v + t$
D) $s = ut + \frac{1}{2}at^2$
Correct Option: A
Explanation: Displacement ( $s$ ) is given by the product of velocity ( $v$ ) and time ( $t$ ).
Which of the following quantities has both magnitude and direction?
A) Speed
B) Distance
C) Velocity
D) Acceleration
Correct Option: C
Explanation: Velocity is a vector quantity as it has both magnitude (speed) and direction.
What is the SI unit of density?
A) Kilogram per cubic meter
B) Meter
C) Kilogram
D) Cubic meter
Correct Option: A
Explanation: Density is defined as mass per unit volume, so its SI unit is kilogram per cubic meter (kg/m³).
Which of the following is the correct formula for density?
A) $\rho = \frac{m}{V}$
B) $\rho = \frac{V}{m}$
C) $\rho = m \times V$
D) $\rho = m + V$
Correct Option: A
Explanation: Density ( $\rho$ ) is calculated as mass ( $m$ ) divided by volume ( $V$ ).
If an object has a mass of 50 kg and occupies a volume of 2 cubic meters, what is its density?
A) 25 kg/m³
B) 100 kg/m³
C) 75 kg/m³
D) 10 kg/m³
Correct Option: A
Explanation: Density = Mass / Volume = 50 kg / 2 m³ = 25 kg/m³.
Which of the following is a scalar quantity?
A) Force
B) Velocity
C) Speed
D) Acceleration
Correct Option: C
Explanation: Speed is a scalar quantity as it only has magnitude, not direction.
What is the SI unit of work?
A) Joule
B) Newton
C) Watt
D) Kilogram
Correct Option: A
Explanation: Work is measured in Joules (J).
What is the formula for calculating work?
A) $W = F \times d$
B) $W = F + d$
C) $W = \frac{F}{d}$
D) $W = F \div d$
Correct Option: A
Explanation: Work ( $W$ ) is given by the product of force ( $F$ ) and displacement ( $d$ ) in the direction of the force.
Which of the following is the correct unit of power?
A) Newton
B) Joule
C) Watt
D) Kilogram
Correct Option: C
Explanation: Power is measured in Watts (W).
What is the formula for calculating power?
A) $P = \frac{W}{t}$
B) $P = W \times t$
C) $P = \frac{t}{W}$
D) $P = W + t$
Correct Option: A
Explanation: Power ( $P$ ) is defined as the rate at which work is done or energy is transferred, so it is calculated as work ( $W$ ) divided by time ( $t$ ).
If a machine does 5000 J of work in 10 seconds, what is its power?
A) 500 W
B) 50 W
C) 5000 W
D) 50000 W
Correct Option: A
Explanation: Power = Work / Time = 5000 J / 10 s = 500 W.
Which of the following is a correct unit for velocity?
A) Meter per second squared
B) Meter per second per second
C) Meter per second
D) Meter squared per second
Correct Option: C
Explanation: Velocity is measured in meters per second (m/s).
What is the formula for calculating velocity?
A) $v = \frac{s}{t}$
B) $v = s \times t$
C) $v = \frac{t}{s}$
D) $v = s + t$
Correct Option: A
Explanation: Velocity ( $v$ ) is given by the ratio of displacement ( $s$ ) to time ( $t$ ).
What is the SI unit of momentum?
A) Kilogram per second
B) Newton
C) Kilogram meter per second
D) Joule
Correct Option: C
Explanation: Momentum is measured in kilogram meter per second (kg·m/s).
Which of the following is the correct formula for momentum?
A) $p = mv$
B) $p = \frac{m}{v}$
C) $p = m \times v$
D) $p = m + v$
Correct Option: A
Explanation: Momentum ( $p$ ) is the product of mass ( $m$ ) and velocity ( $v$ ).
If a car with a mass of 1000 kg is moving at a velocity of 20 m/s, what is its momentum?
A) 500 kg·m/s
B) 20000 kg·m/s
C) 50 kg·m/s
D) 2000 kg·m/s
Correct Option: B
Explanation: Momentum = Mass × Velocity = 1000 kg × 20 m/s = 20000 kg·m/s.
Which of the following quantities is conserved in the absence of external forces?
A) Velocity
B) Acceleration
C) Momentum
D) Force
Correct Option: C
Explanation: In the absence of external forces, momentum is conserved according to the law of conservation of momentum.
What is the SI unit of force constant?
A) Newton
B) Newton per meter
C) Meter
D) Kilogram
Correct Option: B
Explanation: Force constant is measured in Newton per meter (N/m).
Which of the following is the correct formula for Hooke’s Law?
A) $F = kx$
B) $F = \frac{k}{x}$
C) $F = k + x$
D) $F = k \times x$
Correct Option: A
Explanation: Hooke’s Law states that the force exerted by a spring is directly proportional to the displacement from its equilibrium position.
What is the SI unit of spring constant?
A) Newton per meter squared
B) Newton per meter per second
C) Newton per meter
D) Newton per second
Correct Option: C
Explanation: Spring constant is measured in Newton per meter (N/m).
If a spring with a force constant of 100 N/m is compressed by 0.2 meters, what is the force exerted by the spring?
A) 20 N
B) 50 N
C) 10 N
D) 200 N
Correct Option: C
Explanation: According to Hooke’s Law, $F = kx$ , where $k$ is the force constant and $x$ is the displacement. So, $F = (100 N/m) \times (0.2 m) = 10 N$ .
What is the SI unit of electric current?
A) Volt
B) Ampere
C) Ohm
D) Watt
Correct Option: B
Explanation: Electric current is measured in Amperes (A).
What is the formula for calculating electric charge?
A) $Q = It$
B) $Q = I + t$
C) $Q = \frac{I}{t}$
D) $Q = I \times t$
Correct Option: D
Explanation: Electric charge ( $Q$ ) is given by the product of electric current ( $I$ ) and time ( $t$ ).
Which of the following represents Ohm’s Law?
A) $V = IR$
B) $V = \frac{I}{R}$
C) $V = I \times R$
D) $V = I + R$
Correct Option: C
Explanation: Ohm’s Law states that the voltage across a conductor is directly proportional to the current passing through it, with the proportionality constant being the resistance of the conductor.
What is the SI unit of resistance?
A) Volt
B) Ampere
C) Ohm
D) Watt
Correct Option: C
Explanation: Resistance is measured in Ohms (Ω).
What is the formula for calculating resistance?
A) $R = \frac{V}{I}$
B) $R = VI$
C) $R = \frac{I}{V}$
D) $R = V + I$
Correct Option: A
Explanation: Resistance ( $R$ ) is given by the ratio of voltage ( $V$ ) to current ( $I$ ).
If a current of 2 Amperes flows through a conductor when a voltage of 6 Volts is applied, what is the resistance of the conductor?
A) 3 Ω
B) 12 Ω
C) 8 Ω
D) 4 Ω
Correct Option: D
Explanation: Resistance = Voltage / Current = 6 V / 2 A = 3 Ω.
Which of the following is the correct unit of electric potential difference?
A) Ohm
B) Volt
C) Ampere
D) Watt
Correct Option: B
Explanation: Electric potential difference is measured in Volts (V).
What is the SI unit of capacitance?
A) Farad
B) Coulomb
C) Ohm
D) Volt
Correct Option: A
Explanation: Capacitance is measured in Farads (F).
Which of the following is the correct formula for capacitance?
A) $C = \frac{Q}{V}$
B) $C = \frac{V}{Q}$
C) $C = Q \times V$
D) $C = Q + V$
Correct Option: A
Explanation: Capacitance ( $C$ ) is given by the ratio of electric charge ( $Q$ ) to electric potential difference ( $V$ ).
If a capacitor stores a charge of 10 Coulombs when a potential difference of 5 Volts is applied across its plates, what is its capacitance?
A) 50 F
B) 0.5 F
C) 2 F
D) 15 F
Correct Option: B
Explanation: Capacitance = Charge / Voltage = 10 C / 5 V = 2 F.
Which of the following is the correct unit of magnetic flux?
A) Weber
B) Tesla
C) Henry
D) Gauss
Correct Option: A
Explanation: Magnetic flux is measured in Webers (Wb).
What is the SI unit of inductance?
A) Henry
B) Coulomb
C) Weber
D) Gauss
Correct Option: A
Explanation: Inductance is measured in Henrys (H).
Which of the following is the correct formula for inductance?
A) $L = \frac{N}{I}$
B) $L = NI$
C) $L = \frac{I}{N}$
D) $L = N + I$
Correct Option: B
Explanation: Inductance ( $L$ ) is given by the product of the number of turns in the coil ( $N$ ) and the current flowing through it ( $I$ ).
What is the SI unit of magnetic field strength?
A) Tesla
B) Weber
C) Henry
D) Gauss
Correct Option: A
Explanation: Magnetic field strength is measured in Teslas (T).
Which of the following is the correct formula for magnetic field strength?
A) $B = \frac{F}{m}$
B) $B = \frac{m}{F}$
C) $B = F \times m$
D) $B = \frac{F}{t}$
Correct Option: A
Explanation: Magnetic field strength ( $B$ ) is defined as the force acting per unit current per unit length on a current-carrying conductor placed perpendicular to the magnetic field.
If a force of 2 Newtons acts on a current-carrying wire of length 1 meter placed perpendicular to a magnetic field of 3 Teslas, what is the magnitude of the current flowing through the wire?
A) 1 A
B) 6 A
C) 0.5 A
D) 3 A
Correct Option: A
Explanation: Magnetic field strength ( $B$ ) = Force / (Current × Length), so Current = Force / (Magnetic field strength × Length) = 2 N / (3 T × 1 m) = 2/3 A.
Which of the following is the correct unit of electric flux?
A) Weber
B) Tesla
C) Volt
D) Coulomb
Correct Option: A
Explanation: Electric flux is measured in Webers (Wb).
What is the SI unit of magnetic flux density?
A) Tesla
B) Weber
C) Henry
D) Gauss
Correct Option: A
Explanation: Magnetic flux density is measured in Teslas (T).
Which of the following is the correct formula for magnetic flux density?
A) $B = \frac{F}{I}$
B) $B = \frac{I}{F}$
C) $B = F \times I$
D) $B = \frac{F}{t}$
Correct Option: C
Explanation: Magnetic flux density ( $B$ ) is defined as the magnetic flux per unit area perpendicular to the direction of the magnetic field.
If a magnetic field of 2 Teslas produces a magnetic flux of 8 Webers through an area of 4 square meters, what is the magnitude of the magnetic field?
A) 2 T
B) 16 T
C) 4 T
D) 6 T
Correct Option: C
Explanation: Magnetic flux density = Magnetic flux / Area = 8 Wb / 4 m² = 2 T.
Which of the following represents the correct relationship between force, charge, and magnetic field in the Lorentz force equation?
A) $F = q \times B$
B) $F = \frac{q}{B}$
C) $F = q \div B$
D) $F = q + B$
Correct Option: A
Explanation: The Lorentz force equation states that the force experienced by a charged particle moving in a magnetic field is given by $F = q \times B \times v$ , where $q$ is the charge, $B$ is the magnetic field, and $v$ is the velocity of the particle.
What is the SI unit of electric potential?
A) Joule
B) Volt
C) Ampere
D) Coulomb
Correct Option: B
Explanation: Electric potential is measured in Volts (V).
Which of the following is the correct formula for electric potential?
A) $V = \frac{W}{Q}$
B) $V = \frac{Q}{W}$
C) $V = W \times Q$
D) $V = \frac{W}{t}$
Correct Option: A
Explanation: Electric potential ( $V$ ) is defined as the electric potential energy per unit charge.
What is the SI unit of electric potential energy?
A) Volt
B) Joule
C) Watt
D) Ohm
Correct Option: B
Explanation: Electric potential energy is measured in Joules (J).
Which of the following is the correct formula for electric potential energy?
A) $U = QV$
B) $U = \frac{Q}{V}$
C) $U = \frac{V}{Q}$
D) $U = Q + V$
Correct Option: A
Explanation: Electric potential energy ( $U$ ) is given by the product of electric charge ( $Q$ ) and electric potential ( $V$ ).
If a charge of 5 Coulombs is placed in an electric field with a potential difference of 10 Volts, what is its electric potential energy?
A) 50 J
B) 0.5 J
C) 15 J
D) 20 J
Correct Option: A
Explanation: Electric potential energy = Charge × Electric potential = 5 C × 10 V = 50 J.
What is the SI unit of frequency?
A) Hertz
B) Joule
C) Newton
D) Watt
Correct Option: A
Explanation: Frequency is measured in Hertz (Hz).
Which of the following is the correct formula for frequency?
A) $f = \frac{T}{N}$
B) $f = TN$
C) $f = \frac{N}{T}$
D) $f = T + N$
Correct Option: C
Explanation: Frequency ( $f$ ) is defined as the number of cycles per unit time.
What is the SI unit of period?
A) Second
B) Hertz
C) Joule
D) Watt
Correct Option: A
Explanation: Period is measured in seconds (s).
Which of the following is the correct formula for period?
A) $T = \frac{1}{f}$
B) $T = f \times 1$
C) $T = f + 1$
D) $T = \frac{f}{1}$
Correct Option: A
Explanation: Period ( $T$ ) is the reciprocal of frequency, so $T = \frac{1}{f}$ .
If the frequency of a wave is 50 Hz, what is its period?
A) 0.02 s
B) 50 s
C) 0.5 s
D) 2 s
Correct Option: A
Explanation: Period = 1 / Frequency = 1 / 50 Hz = 0.02 s.
Which of the following is the correct formula for wavelength?
A) $\lambda = \frac{v}{f}$
B) $\lambda = \frac{f}{v}$
C) $\lambda = fv$
D) $\lambda = f + v$
Correct Option: A
Explanation: Wavelength ( $\lambda$ ) is defined as the distance between two consecutive crests or troughs of a wave.
What is the SI unit of wavelength?
A) Meter
B) Hertz
C) Joule
D) Pascal
Correct Option: A
Explanation: Wavelength is measured in meters (m).
Which of the following is the correct formula for wave speed?
A) $v = \frac{\lambda}{T}$
B) $v = \frac{T}{\lambda}$
C) $v = \lambda \times T$
D) $v = \frac{\lambda}{f}$
Correct Option: D
Explanation: Wave speed ( $v$ ) is the product of wavelength ( $\lambda$ ) and frequency ( $f$ ).
If the wavelength of a wave is 2 meters and its frequency is 10 Hz, what is its speed?
A) 5 m/s
B) 20 m/s
C) 0.2 m/s
D) 8 m/s
Correct Option: B
Explanation: Wave speed = Wavelength × Frequency = 2 m × 10 Hz = 20 m/s.
What is the SI unit of amplitude?
A) Meter
B) Hertz
C) Pascal
D) No specific unit
Correct Option: A
Explanation: Amplitude is measured in meters (m) for a transverse wave and in pascals (Pa) for a longitudinal wave.
Which of the following is the correct definition of amplitude?
A) The distance between two consecutive crests of a wave
B) The maximum displacement of a particle from its equilibrium position in a wave
C) The number of waves passing a point per unit time
D) The distance traveled by a wave per unit time
Correct Option: B
Explanation: Amplitude is the maximum displacement of a particle from its equilibrium position in a wave.
Which of the following statements about sound waves is correct?
A) Sound waves are electromagnetic waves
B) Sound waves cannot travel through a vacuum
C) Sound waves have the same speed in all media
D) Sound waves cannot be reflected or refracted
Correct Option: B
Explanation: Sound waves require a medium to travel through and cannot propagate through a vacuum.
What is the SI unit of loudness?
A) Decibel
B) Hertz
C) Pascal
D) Meter
Correct Option: A
Explanation: Loudness is measured in decibels (dB).
Which of the following is the correct formula for calculating decibel level?
A) $L = 10 \log_{10} \left(\frac{I}{I_0}\right)$
B) $L = 20 \log_{10} \left(\frac{I}{I_0}\right)$
C) $L = \frac{I}{I_0}$
D) $L = \frac{I_0}{I}$
Correct Option: B
Explanation: The decibel level ( $L$ ) of a sound is given by $L = 20 \log_{10} \left(\frac{I}{I_0}\right)$ , where $I$ is the intensity of the sound and $I_0$ is the reference intensity.
What is the SI unit of frequency in the context of sound waves?
A) Hertz
B) Decibel
C) Pascal
D) Meter
Correct Option: A
Explanation: Frequency of sound waves is measured in Hertz (Hz).
Which of the following is the correct formula for calculating velocity of sound in a medium?
A) $v = \frac{f}{\lambda}$
B) $v = f \times \lambda$
C) $v = f + \lambda$
D) $v = \frac{\lambda}{f}$
Correct Option: D
Explanation: The velocity of sound ( $v$ ) in a medium is given by the product of frequency ( $f$ ) and wavelength ( $\lambda$ ).
What is the SI unit of time period in the context of sound waves?
A) Second
B) Hertz
C) Pascal
D) Meter
Correct Option: A
Explanation: Time period of sound waves is measured in seconds (s).
Which of the following is the correct formula for calculating wavelength of sound waves?
A) $\lambda = \frac{v}{f}$
B) $\lambda = f \div v$
C) $\lambda = f \times v$
D) $\lambda = \frac{v}{t}$
Correct Option: A
Explanation: Wavelength of sound waves ( $\lambda$ ) is the ratio of the velocity of sound ( $v$ ) to its frequency ( $f$ ).
What is the SI unit of pitch?
A) Hertz
B) Decibel
C) Pascal
D) Meter
Correct Option: A
Explanation: Pitch is the perception of the frequency of sound waves and is measured in Hertz (Hz).
Which of the following is the correct formula for calculating pitch?
A) Pitch = Frequency
B) Pitch = Wavelength
C) Pitch = Velocity
D) Pitch = Amplitude
Correct Option: A
Explanation: Pitch corresponds to the frequency of sound waves.
What is the SI unit of amplitude in the context of sound waves?
A) Meter
B) Hertz
C) Pascal
D) No specific unit
Correct Option: D
Explanation: Amplitude of sound waves does not have a specific unit in the context of sound.
Which of the following is the correct definition of amplitude in the context of sound waves?
A) The number of waves passing a point per unit time
B) The distance traveled by a wave per unit time
C) The maximum displacement of a particle from its equilibrium position in a wave
D) The distance between two consecutive crests of a wave
Correct Option: C
Explanation: In the context of sound waves, amplitude is the maximum displacement of a particle from its equilibrium position in a wave.
What is the SI unit of loudness in the context of sound waves?
A) Decibel
B) Hertz
C) Pascal
D) Meter
Correct Option: A
Explanation: Loudness in the context of sound waves is measured in decibels (dB).
Which of the following statements about light waves is correct?
A) Light waves are longitudinal waves
B) Light waves require a medium to propagate
C) Light waves are electromagnetic waves
D) Light waves have the same speed in all media
Correct Option: C
Explanation: Light waves are a type of electromagnetic wave.
What is the SI unit of luminous intensity?
A) Candela
B) Lux
C) Watt
D) Meter
Correct Option: A
Explanation: Luminous intensity is measured in candelas (cd).
Which of the following is the correct formula for calculating luminous flux?
A) $\Phi = I \times A$
B) $\Phi = \frac{I}{A}$
C) $\Phi = \frac{A}{I}$
D) $\Phi = I + A$
Correct Option: A
Explanation: Luminous flux ( $\Phi$ ) is defined as the total quantity of visible light emitted per unit time and is given by the product of luminous intensity ( $I$ ) and solid angle ( $A$ ).
What is the SI unit of luminous flux?
A) Lumen
B) Candela
C) Watt
D) Meter
Correct Option: A
Explanation: Luminous flux is measured in lumens (lm).
Which of the following is the correct formula for calculating illuminance?
A) $E = \frac{L}{d^2}$
B) $E = \frac{d^2}{L}$
C) $E = L \times d^2$
D) $E = L + d^2$
Correct Option: A
Explanation: Illuminance ( $E$ ) is defined as the luminous flux incident per unit area and is given by the ratio of luminous flux ( $L$ ) to the area ( $d^2$ ) on which it falls.
What is the SI unit of illuminance?
A) Lux
B) Candela
C) Lumen
D) Meter
Correct Option: A
Explanation: Illuminance is measured in lux (lx).
Which of the following is the correct formula for calculating luminance?
A) $L = \frac{\Phi}{A}$
B) $L = \frac{A}{\Phi}$
C) $L = \Phi \times A$
D) $L = \Phi + A$
Correct Option: A
Explanation: Luminance ( $L$ ) is defined as the luminous intensity per unit area and is given by the ratio of luminous flux ( $\Phi$ ) to the area ( $A$ ) from which it originates.
What is the SI unit of luminance?
A) Candela per square meter
B) Lux
C) Lumen
D) Meter squared
Correct Option: A
Explanation: Luminance is measured in candelas per square meter (cd/m²).
Which of the following is the correct formula for calculating luminous efficiency?
A) $LE = \frac{L}{\Phi}$
B) $LE = \frac{\Phi}{L}$
C) $LE = \Phi \times L$
D) $LE = \frac{L}{A}$
Correct Option: A
Explanation: Luminous efficiency ( $LE$ ) is defined as the ratio of the luminous flux ( $\Phi$ ) emitted by a light source to the power ( $L$ ) consumed by it.
What is the SI unit of luminous efficiency?
A) Lumen per watt
B) Candela per square meter
C) Lux
D) Meter squared
Correct Option: A
Explanation: Luminous efficiency is measured in lumens per watt (lm/W).
Which of the following is the correct formula for calculating color temperature?
A) $T = \frac{K}{\Phi}$
B) $T = \frac{\Phi}{K}$
C) $T = K \times \Phi$
D) $T = \frac{K}{L}$
Correct Option: A
Explanation: Color temperature ( $T$ ) is defined as the temperature of an ideal black-body radiator that radiates light of a color equivalent to that of the light source, and is given by the ratio of the Kelvin temperature ( $K$ ) to the luminous flux ( $\Phi$ ) emitted by the light source.
What is the SI unit of color temperature?
A) Kelvin
B) Lumen per watt
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Color temperature is measured in Kelvin (K).
Which of the following is the correct formula for calculating color rendering index (CRI)?
A) $CRI = \frac{R}{\Phi}$
B) $CRI = \frac{\Phi}{R}$
C) $CRI = R \times \Phi$
D) $CRI = \frac{R}{L}$
Correct Option: A
Explanation: Color rendering index (CRI) is a measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source, and is given by the ratio of the reference source’s radiance ( $R$ ) to the test source’s radiance ( $\Phi$ ).
What is the SI unit of color rendering index (CRI)?
A) No specific unit
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Color rendering index (CRI) does not have a specific unit.
Which of the following is the correct definition of color rendering index (CRI)?
A) A measure of the ability of a light source to reveal the colors of various objects faithfully
B) A measure of the luminous efficiency of a light source
C) A measure of the color temperature of a light source
D) A measure of the luminance of a light source
Correct Option: A
Explanation: Color rendering index (CRI) is a measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source.
What is the SI unit of radiance?
A) Watt per steradian per square meter
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Radiance is measured in watts per steradian per square meter (W/sr/m²).
Which of the following is the correct formula for calculating radiance?
A) $L = \frac{P}{A}$
B) $L = \frac{A}{P}$
C) $L = P \times A$
D) $L = \frac{P}{\Omega}$
Correct Option: A
Explanation: Radiance ( $L$ ) is defined as the radiant power ( $P$ ) per unit solid angle ( $A$ ) per unit projected source area, and is given by the ratio of radiant power to the area.
What is the SI unit of radiant power?
A) Watt
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Radiant power is measured in watts (W).
Which of the following is the correct definition of radiant power?
A) The ability of a light source to reveal the colors of various objects faithfully
B) The luminous efficiency of a light source
C) The rate at which light energy is emitted, transmitted, or received per unit time
D) The color temperature of a light source
Correct Option: C
Explanation: Radiant power is defined as the rate at which light energy is emitted, transmitted, or received per unit time.
What is the SI unit of solid angle?
A) Steradian
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Solid angle is measured in steradians (sr).
Which of the following is the correct formula for calculating solid angle?
A) $\Omega = \frac{A}{d^2}$
B) $\Omega = \frac{d^2}{A}$
C) $\Omega = A \times d^2$
D) $\Omega = \frac{A}{L}$
Correct Option: A
Explanation: Solid angle ( $\Omega$ ) is defined as the ratio of the area ( $A$ ) of a surface intercepted by a cone to the square of the distance ( $d$ ) from the vertex of the cone to the center of the sphere.
What is the SI unit of luminous flux density?
A) Lumen per square meter
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Luminous flux density is measured in lumens per square meter (lm/m²).
Which of the following is the correct formula for calculating luminous flux density?
A) $D = \frac{\Phi}{A}$
B) $D = \frac{A}{\Phi}$
C) $D = \Phi \times A$
D) $D = \frac{\Phi}{L}$
Correct Option: A
Explanation: Luminous flux density ( $D$ ) is defined as the luminous flux ( $\Phi$ ) per unit area ( $A$ ) and is given by the ratio of luminous flux to area.
What is the SI unit of spectral radiance?
A) Watt per steradian per square meter per meter
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Spectral radiance is measured in watts per steradian per square meter per meter (W/sr/m²/µm).
Which of the following is the correct formula for calculating spectral radiance?
A) $L_{\lambda} = \frac{P_{\lambda}}{A \times \Omega \times \Delta \lambda}$
B) $L_{\lambda} = \frac{A \times \Omega \times \Delta \lambda}{P_{\lambda}}$
C) $L_{\lambda} = P_{\lambda} \times A \times \Omega \times \Delta \lambda$
D) $L_{\lambda} = \frac{P_{\lambda}}{A + \Omega + \Delta \lambda}$
Correct Option: A
Explanation: Spectral radiance ( $L_{\lambda}$ ) is defined as the radiant power per unit area per unit solid angle per unit wavelength interval and is given by the ratio of radiant power ( $P_{\lambda}$ ) to the product of area ( $A$ ), solid angle ( $\Omega$ ), and wavelength interval ( $\Delta \lambda$ ).
What is the SI unit of spectral irradiance?
A) Watt per square meter per meter
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Spectral irradiance is measured in watts per square meter per meter (W/m²/µm).
Which of the following is the correct formula for calculating spectral irradiance?
A) $E_{\lambda} = \frac{P_{\lambda}}{A \times \Delta \lambda}$
B) $E_{\lambda} = \frac{A \times \Delta \lambda}{P_{\lambda}}$
C) $E_{\lambda} = P_{\lambda} \times A \times \Delta \lambda$
D) $E_{\lambda} = \frac{P_{\lambda}}{A + \Delta \lambda}$
Correct Option: A
Explanation: Spectral irradiance ( $E_{\lambda}$ ) is defined as the radiant power per unit area per unit wavelength interval and is given by the ratio of radiant power ( $P_{\lambda}$ ) to the product of area ( $A$ ) and wavelength interval ( $\Delta \lambda$ ).
What is the SI unit of radiant intensity?
A) Watt per steradian
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Radiant intensity is measured in watts per steradian (W/sr).
Which of the following is the correct formula for calculating radiant intensity?
A) $I = \frac{P}{\Omega}$
B) $I = \frac{\Omega}{P}$
C) $I = P \times \Omega$
D) $I = \frac{P}{A}$
Correct Option: A
Explanation: Radiant intensity ( $I$ ) is defined as the radiant power ( $P$ ) emitted, transmitted, or received by a surface per unit solid angle ( $\Omega$ ).

What is the SI unit of radiosity?
A) Watt per square meter
B) Kelvin
C) Lux
D) Candela per square meter
Correct Option: A
Explanation: Radiosity is measured in watts per square meter (W/m²).
Which of the following is the correct formula for calculating radiosity?
A) $J = \frac{P}{A}$
B) $J = \frac{A}{P}$
C) $J = P \times A$
D) $J = \frac{P}{\Omega}$
Correct Option: A
Explanation: Radiosity ( $J$ ) is defined as the total radiant power ( $P$ ) emitted, transmitted, or received by a surface per unit area ( $A$ ).