Grade 11 : Physics - Units (Set 1) | Concept of Maths

Question 1

1. In the International System of Units (SI), which unit is used to measure the luminous intensity of a light source?

A) Lumen

B) Lux

C) Candela

D) Watt

Answer

Correct Answer: C

Solution: The SI base unit of luminous intensity is the Candela (symbol: $cd$). It measures the luminous power per unit solid angle emitted by a point light source in a particular direction.

Question 2

2. A researcher is calculating the angle subtended by a spherical surface at its center. What is the SI unit for this 'solid angle'?

A) Radian

B) Steradian

C) Degree

D) Candela

Answer

Correct Answer: B

Solution: The SI unit for a plane angle is the radian, whereas the SI unit for a solid angle is the Steradian (symbol: $sr$).

Question 3

3. Which of the following is considered a 'Fundamental Unit' in the SI system?

A) Kilogram

B) Newton

C) Joule

D) Pascal

Answer

Correct Answer: A

Solution: Fundamental units are the units of base quantities. In SI, there are seven: Meter ($m$), Kilogram ($kg$), Second ($s$), Ampere ($A$), Kelvin ($K$), Mole ($mol$), and Candela ($cd$). Kilogram is a base unit, while Newton, Joule, and Pascal are derived units.

Question 4

4. A high-speed train travels at a velocity of $180\text{ km/h}$. What is its speed expressed in the SI unit of velocity ($m/s$)?

Question 5

5. The pressure exerted by a fluid is measured in Pascals ($Pa$). Which of the following represents $1\text{ Pascal}$ in terms of base units?

A) $kg \cdot m \cdot s^{-2}$

B) $kg \cdot m^{-1} \cdot s^{-2}$

C) $kg \cdot m^{2} \cdot s^{-2}$

D) $kg \cdot m^{-2} \cdot s^{-1}$

Answer

Correct Answer: B

Solution: Pressure is Force per unit Area ($P = F/A$). Units of Force ($N$) = $kg \cdot m \cdot s^{-2}$ Units of Area = $m^{2}$ Therefore, $$P = \frac{kg \cdot m \cdot s^{-2}}{m^2} = kg \cdot m^{-1} \cdot s^{-2}$$

Question 6

6. An atomic physicist measures the radius of a nucleus to be $1\text{ Angstrom } (\text{Å})$. This length is equivalent to:

A) $10^{-10}\text{ m}$

B) $10^{-9}\text{ m}$

C) $10^{-12}\text{ m}$

D) $10^{-15}\text{ m}$

Answer

Correct Answer: A

Solution: By dimension definition, $1$ Angstrom ($1\text{ Å}$) is exactly equivalent to $10^{-10}$ meters.

Question 7

7. Which of the following is NOT a unit of distance?

A) Light year

B) Parsec

C) Barn

D) Astronomical Unit

Answer

Correct Answer: C

Solution: A Barn is a specific measurement unit of Area ($10^{-28}\text{ m}^2$), often leveraged in cross-sectional nuclear physics. Light year, Parsec, and Astronomical Unit (AU) map geometric spatial distances.

Question 8

8. A motor is rated at $10\text; Horsepower (hp)}$. Approximately how many Watts ($W$) is this?

A) $74.6\text{ W}$

B) $7460\text{ W}$

C) $1000\text{ W}$

D) $550\text{ W}$

Answer

Correct Answer: B

Solution: $1\text{ horsepower (hp)} \approx 746\text{ Watts}$. Thus, $10\text{ hp} = 10 \times 746 = 7460\text{ W}$.

Question 9

9. The prefix 'Giga' represents which multiplier?

A) $10^{3}$

B) $10^{6}$

C) $10^{-9}$

D) $10^{9}$

Answer

Correct Answer: D

Solution: In the metric system factor indices: <ul> <li>Kilo = $10^3$</li> <li>Mega = $10^6$</li> <li>Giga = $10^9$</li> <li>Tera = $10^{12}$</li> </ul>

Question 10

10. What is the SI unit of thermodynamic temperature?

A) Kelvin

B) Celsius

C) Fahrenheit

D) Rankine

Answer

Correct Answer: A

Solution: The standard SI base reference unit for absolute system temperature is the Kelvin ($K$).

Question 11

11. A signal frequency is given as $500\text{ MHz}$. This value in Hertz ($Hz$) is:

A) $500 \times 10^3\text{ Hz}$

B) $500 \times 10^4\text{ Hz}$

C) $500 \times 10^6\text{ Hz}$

D) $500 \times 10^9\text{ Hz}$

Answer

Correct Answer: C

Solution: The prefix 'Mega' ($M$) denotes structural factor $10^6$. Therefore, $500\text{ MHz} = 500 \times 10^6\text{ Hz}$.

Question 12

12. Which of the following is a supplementary unit in SI?

A) Meter

B) Radian

C) Ampere

D) Mole

Answer

Correct Answer: B

Solution: The standard SI architecture structures Radian (plane structural angle) and Steradian (solid angle calculations) as supplementary metrics.

Question 13

13. The unit of surface tension in SI system is:

A) $N \cdot m$

B) $N \cdot m^2$

C) $N/m$

D) $N/m^2$

Answer

Correct Answer: C

Solution: Surface tension ($T$) acts as dimensional Force ($F$) exerted across cross length lines ($l$). $$T = \frac{F}{l}$$ Hence, the unit tracks directly as Newton per meter ($N/m$).

Question 14

14. $1\text{ unified atomic mass unit (u)}$ is approximately equal to:

A) $1.66 \times 10^{-27}\text{ kg}$

B) $1.66 \times 10^{-24}\text{ kg}$

C) $9.1 \times 10^{-31}\text{ kg}$

D) $6.02 \times 10^{23}\text{ kg}$

Answer

Correct Answer: A

Solution: $1\text{ u}$ equals $\frac{1}{12}$ the mass of a rest carbon-12 nucleus, scaling around $1.66 \times 10^{-27}\text{ kg}$.

Question 15

15. Which of these is the SI unit for the amount of substance?

A) Gram

B) Kilogram

C) Cubic meter

D) Mole

Answer

Correct Answer: D

Solution: The foundational metric base unit for aggregate chemical element counts is the Mole ($mol$).

Question 16

16. How many meters are there in $1\text{ nanometer (nm)}$?

A) $10^{-6}\text{ m}$

B) $10^{-9}\text{ m}$

C) $10^{-12}\text{ m}$

D) $10^{-3}\text{ m}$

Answer

Correct Answer: B

Solution: The micro prefix 'nano' scales factor variables down to $10^{-9}$. Thus, $1\text{ nm} = 10^{-9}\text{ m}$.

Question 17

17. If a car covers a distance of $100\text{ meters}$ in $5\text{ seconds}$, its average speed in SI units is:

A) $20\text{ m/s}$

B) $500\text{ m/s}$

C) $0.05\text{ m/s}$

D) $20\text{ km/h}$

Answer

Correct Answer: A

Solution: $$\text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{100\text{ m}}{5\text{ s}} = 20\text{ m/s}$$

Question 18

18. Which of the following units is used for measuring electric resistance?

A) Volt

B) Ampere

C) Ohm

D) Farad

Answer

Correct Answer: C

Solution: Electrical pathway resistance is sized in Ohm metrics ($\Omega$).

Question 19

19. $1\text{ Joule}$ is equivalent to:

A) $1\text{ N} \cdot \text{ m}^2$

B) $1\text{ N} \cdot \text{ m}$

C) $1\text{ N/m}$

D) $1\text{ kg} \cdot \text{ m/s}$

Answer

Correct Answer: B

Solution: Work Evaluated = Force $\times$ Displacement. Therefore, $1\text{ Joule} = 1\text{ Newton} \times 1\text{ meter} = 1\text{ N} \cdot \text{ m}$.

Question 20

20. The SI unit of power is the Watt. $1\text{ Watt}$ is equal to:

A) $1\text{ Joule} \cdot \text{ second}$

B) $1\text{ Newton/second}$

C) $1\text{ kg} \cdot \text{ m}^2/\text{s}^2$

D) $1\text{ Joule/second}$

Answer

Correct Answer: D

Solution: Power evaluates work run speed variations ($P = W/t$). Thus, $1\text{ Watt} = 1\text{ Joule} / 1\text{ second}$.

Accepted Answer

Correct Answer: D

Solution: To convert $km/h$ to $m/s$, multiply the magnitude value by $\frac{5}{18}$: $$180 \times \frac{5}{18} = 10 \times 5 = 50\text{ m/s}$$

Grade 11 : Physics - Units (Set 1) | Concept of Maths