MCQ's On Units and Measurements

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Standard Units of Measurements are used for measuring physical quantities such as length, time, and mass. For instance, length is measured in meters. The quantities used to describe the laws of physics are known as physical quantities. Thus, length, pressure, mass, temperature, time, resistance, and current are the physical quantities. Physical quantities are classified as:

Fundamental quantities or base quantities: The quantities that remain independent of each other are referred to as the base quantities.
Derived quantities: All the other quantities that can further be expressed in terms of fundamental quantities are known as derived quantities.

The standard reference that is used to measure a physical quantity is known as the unit. There are two types of units: fundamental units and derived units.

Ques 1. __________ has the same dimensions that of kinetic energy.

Work
Force
Momentum
Pressure

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Ans: a Work

Explanation: The work is done whenever energy changes from one form to another. The measurements of both energy and work is done in Joules. The work done is equal to the amount of energy transferred.

Energy = Work = Displacement x Force

Force = Mass x Acceleration

Unit of Force = kg m/s²

So, Force = Mass x Length/Time² = [MLT^-2]

Dimension of Displacement = [L]

So the dimension of Work or Energy = [MLT^-2] x [L] = [ML²T^-2]

Ques 2. Select the correct option for the dimensional formula of the magnetic field

M^-1LTA^-2
MT^-2L^-1
M^-1A^-2TL-1
MT^-1L^-2

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Ans: b. MT^-2L^-1

Explanation: Force = Charge x Magnetic Field x Velocity

So, Magnetic Field (B) = Force / (Charge x velocity)

Since, Velocity = Distance/Time

Hence, the dimensional formula of velocity is LT^-1

Electric charge = Current x Time = IT^-1

Force = Mass x acceleration = M x T^-2

On substituting the dimensional values of velocity, force, and current in the magnetic field equation, we get

B = M1T^-2L^-1

Ques 3. What is the unit of Energy?

Ohm
Newton
Electron Volt
Farad

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Ans: c. Electron Volt

Explanation: An electrically charged particle when passed through the potential V has an energy E= qV, where q is the charge of the particle and V is the potential. The electron volt is commonly used in nuclear and atomic physics as the unit of energy.

1 Electron Volt = 1.6 x 10^-19Joules

Ques 4. What are the complete set of base and derived units known as?

Base Units
Fundamental Units
System of Units
None of the above

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Ans: c. System of Units

Explanation: When certain units are considered as basic and the other units are derived from them, is known as System of Units. There are four fundamental units in physics which are Ampere, Second, kilogram, and meter.

Ques 5. Which method is used to measure the distance of other planets from the earth?

Parallax Method
Meter Scale
Both a and b methods
None of the above

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Ans: a. Parallax Method

Explanation: When an object is viewed from two different positions, the change or displacement in the position of that object is parallax. This method helps the astronomers to measure the distances of the stars or planets that are far away by using trigonometry.

Ques 6. What is the value of 1 light-year?

9.46 km
9.46 m
9.46 x 10¹⁵ m
9.46 x 10^-15 m

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Ans: c. 9.46 x 10¹⁵ m

Explanation: The distance traveled by light in one year is known as Light year. A light year is used as a unit to express the astronomical distances. It can also be defined as the distance traveled by the light when it travels in a vacuum in one Julian year.

Ques 7. The frequency of the sound waves are measured in

Amperes
Metre
Newton
Hertz

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Ans: d Hertz

Explanation: The measurement of the vibrations of the sound in one second is known as Frequency. A healthy ear can hear the sound with frequency ranging from very low (20 Hz) to very high (20,000 Hz). By counting the number of crests, wave energy can be determined. The waves with greater frequency have a higher number of crests.

Ques 8. What is the unit of Luminous Intensity?

Hertz
Meters
Candela
Kilogram

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Ans: c. Candela

Explanation: The SI unit of Luminous Intensity is Candela, which is used to measure the visual intensity of the sources of light like bulbs in torches, light bulbs, etc. Luminous intensity can be understood as the luminous flux that is emitted by any source in a particular direction per unit solid angle. The unit to measure brightness in terms of luminous intensity in Candela is candela/ m².

Brightness, L = I/A cosθ

Where the luminous intensity of a source be I candela on an Area referred to as A, then we can say that the projected area to measure the brightness is A cos ?.

Ques 9. What is the value of 1 astronomical unit?

1.496 x 10^-11 m
1.496 x 10¹² m
1.496 m
1.496 x 10¹¹ m

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Ans: d. 1.496 x 10¹¹ m

Explanation: The astronomical unit is a unit of length. It is approximately equal to the mean or average distance from Earth to the sun is known as Astronomical unit. To measure the distances within the Solar system, astronomical unit is generally used. The light of sun travels for 499 seconds to reach earth and the distance is called as 1 astronomical unit.

Ques 10. How far is moon located from the earth?

109 m
1010 m
108 m
110 m

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Ans: c. 108 m

Explanation: The moon is located at an average distance of 238,800 miles from the earth. This distance is approximately equal to 108 times the diameter of the moon. Moon is the only natural satellite of the Earth. The light takes 1.3 light seconds to travel to the earth from the moon.

Read Also:

NCERT Solutions for Class 11 Physics	Class 11 Physics Notes	Physics Formulas
Fundamental Forces in Nature	Measurement of Mass	Lorentz Force
Reduction Potential	Nernst Equation	Dimensional Analysis
Semiconductor Diode	Law of Inertia	Fundamental Forces in Nature

CBSE CLASS XII Related Questions

1.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

View Solution

2.
A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.

3.
An electric field $\vec{E}$ is established across the ends of a cylindrical conductor of length L and area of cross-section A. Discuss how electrons attain an average velocity, independent of time. Hence, obtain a relation between current in the conductor and this ‘average velocity’ of electrons.

View Solution

4.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

The total charge of the two spheres is conserved.
Both spheres attain the same potential.
The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2)}{(r_1 + r_2)}$
The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2) (r_1 + r_2)}{r_1 r_2}$

View Solution

5.
The resistance of a metal wire at $ 20^\circ \text{C} $ is $ 1.05 \, \Omega $ and at $ 100^\circ \text{C} $ is $ 1.38 \, \Omega $. Determine the temperature coefficient of resistivity of this metal.

View Solution

6.
Capacitors are manufactured with certain standard capacitances and working voltages. However, these standard values may not be the ones that are actually needed in a particular application. Two or more capacitors can be grouped in series or in parallel to achieve desired capacitance and voltage. When connected in series, the total capacitance decreases while the voltage rating increases, whereas in parallel connections, the total capacitance increases and maintains the same voltage rating. A capacitor stores energy in the electric field between its plates and stored energy is proportional to the square of the voltage and capacitance $U = \frac{1}{2}CV^2$, where symbols have their usual meanings.
Two capacitors, one of $3 \ \mu$F and the other of $6 \ \mu$F, are connected in series in the circuit as shown in the figure, for a long time. }

MCQ's On Units and Measurements

CBSE CLASS XII Related Questions

1.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

4.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

5.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

Similar Physics Concepts

Comments

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MCQ's On Units and Measurements

CBSE CLASS XII Related Questions

1.Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

4.Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

5. The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

1.
Derive an expression for the capacitance of a parallel plate capacitor of plate area A and plate separation d with air present between the plates.

4.
Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

5.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.