9th Physics Chapter1 Physical Quantities and Measurement

Question 1. How does a Vernier caliper achieve higher precision compared to a regular ruler?
Answer:

A Vernier caliper achieves higher precision by incorporating a sliding Vernier scale that allows for measurements to be read to a fraction of the smallest division on the main scale.

 

Question 2. Define relative error and percentage error in the context of measurements, and explain how they are calculated.
Answer:

Relative error is the ratio of the absolute error to the measured value. Percentage error is the relative error expressed as a percentage of the measured value.

 

Question 3. Express 6,300,000 in scientific notation
Answer:

6,300,000 in scientific notation is 6.3 x 10^6.

Question 4. Describe a simple method for measuring the length of an irregularly shaped object.
Answer:

Use a ruler or a measuring tape to measure the length along its longest dimension, ensuring the measuring tool follows the contours of the object.

 

Question 5. Explain the significance of the coefficient in scientific notation
Answer:

The coefficient in scientific notation represents the significant digits of a number, providing the essential numerical information.

 

Question 6. precision and accuracy in measurements, providing examples to illustrate each concept.
Answer:

Precision refers to the repeatability of measurements, while accuracy measures how close measurements are to the true value. A group of measurements clustered closely together is precise but may not be accurate if they deviate from the true value.

 

Question 7. Describe the procedure for measuring the diameter of a small sphere using a screw gauge.
Answer:

Place the sphere between the anvil and the spindle of the screw gauge. Rotate the thimble until the sphere is firmly held. Read the main scale and the circular scale to obtain an accurate measurement.

Question 8. Describe the proper technique for using a stopwatch to measure time accurately.
Answer:

Start the stopwatch when the event begins and stop it precisely when the event ends. Avoid parallax error by ensuring that you view the stopwatch directly from the front.

Question 9. How is a number written in scientific notation?
Answer:

A number in scientific notation is written as a coefficient multiplied by 10 raised to a power (e.g., 4.2 x 10^5).

Question 10. How can you determine the center of mass on a lever balance?
Answer:

The center of mass on a lever balance is found by adjusting the position of the standard masses until the lever is balanced, indicating that the center of mass is directly below the pivot point.

Question 11. Explain the principle of operation of an electronic balance.
Answer:

An electronic balance operates based on the principle of electromagnetic force compensation. The balance measures the force needed to counteract the gravitational force on the object and converts it into a mass measurement.

 

Question 12. Why is an electronic balance considered more accurate than a spring balance?
Answer:

Electronic balances provide higher accuracy because they measure the force directly, while spring balances measure the extension of a spring, which may be influenced by factors like temperature.

Question 13. Sound:
Answer:

Description: Sound physics explores the production, transmission, and effects of sound waves.

Example: Hearing a bell ring or feeling vibrations when playing a musical instrument.

 

Question 14. Discuss the concept of significant figures and their importance in conveying the precision of a measurement.
Answer:

Significant figures indicate the precision of a measurement, including all certain digits and one uncertain digit. They help convey the level of confidence in a measurement.

 

Question 15. Discuss the significance of using standard units in scientific measurements and their role in fostering international collaboration in research.
Answer:

Standard units provide a common language for scientists globally, facilitating communication and comparison of results. They ensure consistency and accuracy in scientific endeavors.

 

Question 16. Describe a method for measuring the volume of an irregularly shaped solid.
Answer:

Submerge the object in a known volume of water, and measure the change in water level. The change in volume of water is equal to the volume of the object.

 

Question 17. When measuring a liquid's volume in a measuring cylinder, why is it important to avoid parallax error?
Answer:

Parallax error can lead to inaccurate readings. To avoid it, make sure the eye is directly in line with the level of the liquid, preventing any distortion in volume measurement.

Question 18. Explain the use of a meter rule in physics experiments.
Answer:

A meter rule is used to measure length or distance in physics experiments. It is a straight, flat, and thin instrument marked in centimeters and millimeters.

Question 19. Mechanics:
Answer:

Description: Mechanics studies the motion and behavior of objects.

Example: Understanding why a ball rolls downhill or how a car comes to a stop when brakes are applied.

Question 20. How does a screw gauge achieve higher precision compared to a ruler?
Answer:

A screw gauge achieves higher precision by having a smaller least count, allowing for more accurate measurements of small dimensions

 

Question 21. Electricity and Magnetism:
Answer:

Description: This branch covers the study of electric charges, currents, and magnetic fields.

Example: Turning on a light switch (electricity) or using a magnetic compass.

 

Question 22. How is the least count of a screw gauge calculated?
Answer:

The least count (LC) is calculated by dividing the pitch of the screw by the total number of divisions on the circular scale. Mathematically, LC = Pitch / Total number of divisions.

 

Question 23. Explain why measurement is a fundamental aspect of scientific inquiry, and how it contributes to the development of scientific theories.
Answer:

Measurement provides a quantitative basis for observations, allowing scientists to gather data, analyze patterns, and formulate theories. It adds precision and objectivity to scientific investigations.

 

Question 24. Compare the precision of a Vernier caliper and a ruler for measuring length.
Answer:

A Vernier caliper is more precise than a ruler because it can measure lengths to a fraction of a millimeter, whereas a ruler typically provides measurements in whole millimeters.

Question 25. Discuss the concept of dimensional analysis and how it can be used to check the correctness of equations in physics.
Answer:

Dimensional analysis involves examining the dimensions (units) of quantities in an equation to ensure that both sides are equivalent. It helps verify the correctness of equations and identify errors.

Question 26. Why is it important to check and calibrate measuring instruments regularly?
Answer:

Regular calibration ensures that measuring instruments provide accurate and reliable measurements. Changes in conditions or wear over time can affect their accuracy.

Question 27. How does scientific notation make arithmetic operations easier?
Answer:

Scientific notation simplifies arithmetic operations by allowing for easier multiplication, division, addition, and subtraction of numbers with exponents.

 

Question 28. Explain the principle of operation of a screw gauge.
Answer:

A screw gauge measures the dimensions of an object by translating the linear motion of a screw into rotational motion. The movement of the screw advances a spindle, allowing precise measurements to be made.

Question 29. Explain the working principle of an electronic balance.
Answer:

An electronic balance works by measuring the force exerted by an object due to gravity. The force is converted into an electrical signal, which is then used to determine the mass of the object.

 

Question 30. Discuss the difference between mass and weight, and explain how mass is measured.
Answer:

Mass is the amount of matter in an object, while weight is the force of gravity acting on it. Mass is measured using a balance or a scale.

Question 31. Explain the concept of expressing measurements in scientific notation and how it aids in handling large or small values.
Answer:

Scientific notation involves representing a number as a coefficient multiplied by a power of 10. It is particularly useful for handling numbers with many zeros, simplifying calculations.

 

Question 32. When is it appropriate to use scientific notation in physics calculations?
Answer:

Scientific notation is often used in physics calculations when dealing with very large or very small measurements, such as distances in space or particle sizes

Question 33. Why is scientific notation useful in physics?
Answer:

Scientific notation is useful in physics because it simplifies the representation of numbers involved in very large or very small measurements.

Question 34. Provide examples of how measurements are applied in everyday life, beyond scientific research.
Answer:

Examples include cooking (measuring ingredients), construction (measuring distances and angles), and shopping (measuring quantities for buying and selling).

 

Question 35. Differentiate between precision and accuracy in measurements, providing examples.
Answer:

Accuracy refers to how close a measurement is to the true value, while precision is the degree of consistency in repeated measurements. An accurate and precise measurement hits the target consistently, while inaccurate but precise measurements cluster around a common value.

 

Question 36. Light:
Answer:

Description: Light physics studies the properties and behaviors of light.

Example: Seeing a rainbow after rain or understanding how a lens focuses sunlight.

Question 37. Explain the concept of least count in Vernier calipers.
Answer:

The least count is the smallest measurement that can be read on a Vernier caliper. It is determined by dividing the smallest division on the main scale by the total number of divisions on the Vernier scale.

 

Question 38. Geophysics:
Answer:

Description: Geophysics explores the physical properties and processes of the Earth.

Example: Studying seismic waves during an earthquake or understanding Earth’s magnetic field.

 

Question 39. What is a physical quantity, and how does it differ from a scalar quantity?
Answer:

A physical quantity is a characteristic that can be measured. Scalars have only magnitude, while vectors have both magnitude and direction.

Question 40. Explain the principle of operation of a lever balance in measuring mass.
Answer:

A lever balance operates based on the principle of a lever. The mass to be measured is placed on one side, and standard masses are added to the other side until equilibrium is achieved.

 

Question 41. If the zero on the Vernier scale does not align perfectly with the main scale, how would you compensate for the error in measurement?
Answer:

If the zero on the Vernier scale is not aligned, the reading should be adjusted by the number of divisions that are misaligned, multiplied by the least count of the Vernier caliper.

 

Question 42. Explain the concept of zero error in a screw gauge.
Answer:

Zero error in a screw gauge occurs when the zero mark on the circular scale does not align with the reference line on the main scale. It needs to be taken into account while making measurements.

 

Question 43. How do you measure the diameter of a small sphere using a Vernier caliper?
Answer:

To measure the diameter of a small sphere using a Vernier caliper, place the sphere between the jaws and close them gently. Read the main scale and Vernier scale to obtain an accurate measurement

Question 44. What precautions should be taken when using an electronic balance?
Answer:

: Precautions include ensuring the balance is on a stable surface, avoiding air currents, and handling the balance gently. Additionally, it’s crucial to tare the balance before measurements.

 

Question 45. What is the difference between an inside and outside measurement on a Vernier caliper?
Answer:

For outside measurements, the object is placed between the outside jaws, while for inside measurements, the object is held between the inside jaws. The readings are taken accordingly.

 

Question 46. How do you read the measurement on a Vernier caliper?
Answer:

To read the measurement on a Vernier caliper, align the zero mark on the Vernier scale with the closest mark on the main scale. The Vernier scale’s reading indicates the fraction of a division on the main scale.

Question 47. Why is a screw gauge preferred over a Vernier caliper for certain measurements?
Answer:

A screw gauge is preferred for measuring smaller dimensions with higher precision because it typically has a smaller least count compared to a Vernier caliper.

 

Question 48. Differentiate between a meter rule and a measuring tape
Answer:

A meter rule is a rigid, flat, and straight measuring instrument, while a measuring tape is a flexible, coiled instrument. Measuring tapes are suitable for measuring curved or irregular surfaces.

Question 49. Differentiate between a lever balance and an electronic balance in terms of operation and precision.
Answer:

A lever balance operates mechanically by comparing torques, while an electronic balance uses sensors and electronics to measure mass. Electronic balances typically offer higher precision.

Question 50. Nuclear Physics:
Answer:

Description: Nuclear physics studies the properties and behavior of atomic nuclei.

Example: Exploring the process of nuclear fission in power plants or understanding radioactive decay

Question 51. Discuss common sources of errors in measurements and strategies to minimize them.
Answer:

Errors can result from instrument limitations, human limitations, or external factors. Minimizing errors involves using appropriate instruments, repeating measurements, and calibrating instruments regularly.

Question 52. Can Vernier calipers be used to measure depth? If so, how?
Answer:

Yes, Vernier calipers can measure depth using the depth gauge. The depth gauge is extended, and the measurement is taken by placing the end of the caliper on the bottom of the object.

Question 53. If the circular scale has 100 divisions and the pitch is 1.0 mm, what is the least count of the screw gauge?
Answer:

Given LC = Pitch / Total number of divisions, LC = 1.0 mm / 100 divisions = 0.01 mm or 0.001 cm.

Question 54. What is scientific notation?
Answer:

Scientific notation is a way of expressing very large or very small numbers by using powers of 10.

Question 55. Convert 9.8 x 10^3 to standard notation.
Answer:

9.8 x 10^3 in standard notation is 9800.

Question 56. What is the purpose of a physical balance in a laboratory?
Answer:

A physical balance is used to measure mass. It compares the mass of an object to standard masses and provides an accurate measurement

 

Question 57. Heat:
Answer:

Description: Heat physics deals with the transfer and properties of heat energy.

Example: Feeling the warmth of sunlight on your skin or heating water on a stove.

 

Question 58. Explain the correct method for reading the volume from a measuring cylinder.
Answer:

Read the volume at the bottom of the meniscus, which is the curved surface of the liquid. Ensure that the cylinder is on a flat surface and eye level with the liquid level.

 

Question 59. How would you use a micrometer screw gauge to measure the thickness of a thin sheet?
Answer:

Place the thin sheet between the anvil and the spindle of the micrometer screw gauge. Turn the thimble until the sheet is firmly held, and then read the measurement from the main scale and the rotating thimble

 

Question 60. What is the purpose of a Vernier caliper in a physics laboratory?
Answer:

A Vernier caliper is used to measure the internal and external dimensions of objects with high precision, such as the length or diameter of a cylindrical object.

Question 61. Atomic Physics:
Answer:

Description: Atomic physics examines the structure and behavior of atoms.

Example: Learning about electrons orbiting an atomic nucleus or understanding atomic energy levels.

Question 62. Explain a simple method for measuring a short duration of time without using a clock.
Answer:

Counting the number of heartbeats or the number of oscillations of a simple pendulum can be used for short-time measurements.

 

Question 63. Plasma Physics:
Answer:

Description: Plasma physics deals with the behavior of ionized gases, known as plasmas.

Example: Observing the glow of neon lights or understanding the properties of the sun’s outer layer.

Question 64. Describe a situation where a micrometer screw gauge would be more suitable than a Vernier caliper for measurement.
Answer:

A micrometer screw gauge is more suitable for measuring very small lengths or thicknesses, such as the diameter of a thin wire, where higher precision is required compared to a Vernier caliper.

Question 65. Define the term "pitch" in the context of a screw gauge.
Answer:

The pitch is the distance moved by the screw for one complete rotation. It is an essential parameter for determining the least count of the screw gauge.

 

Question 66. When would you choose to use a Vernier caliper over other measuring instruments like a ruler or a micrometer screw gauge?
Answer:

A Vernier caliper is chosen when high precision is required for measuring lengths or dimensions of objects, especially when dealing with cylindrical or irregular shapes, where a ruler or micrometer screw gauge may not be as effective

Question 67. What is the main scale and the screw scale on a screw gauge, and how are they used for measurement?
Answer:

The main scale provides the primary measurement in millimeters, while the screw scale allows for more precise measurements. The combination of the two scales provides an accurate measurement.

Question 68. Explain the importance of using standard units in scientific measurements.
Answer:

Standard units provide a universally accepted and consistent way of expressing measurements, ensuring clarity and accuracy in scientific communication

Question 69. Why are significant figures important in expressing measured values, and how are they determined?
Answer:

Significant figures indicate the precision of a measurement. They include all certain digits plus one uncertain digit. Zeros between significant figures and trailing zeros in a decimal number are considered significant.

Question 70. How does a digital stopwatch differ from an analog stopwatch in terms of operation and accuracy?
Answer:

Digital stopwatches use electronic components for precision, while analog stopwatches rely on mechanical mechanisms. Digital stopwatches are often more accurate and easier to read.

 

Question 71. Explore the limitations inherent in measurement devices and how these limitations may impact the accuracy of experimental results.
Answer:

Measurement devices have finite precision and sensitivity. Understanding these limitations helps scientists account for potential errors in their experiments.

 

Question 72. Explore the ethical considerations associated with measurements, especially in research and reporting of scientific findings.
Answer:

Ethical considerations include accurate reporting, transparency about measurement methods, and avoiding manipulation of data to ensure the integrity of scientific research.

 

Question 73. Explain the main components of a Vernier caliper.
Answer:

A Vernier caliper consists of a main scale, a sliding Vernier scale, an inside jaws for internal measurements, an outside jaws for external measurements, and a depth gauge.

 

Question 74. What is the purpose of the main scale on a Vernier caliper?
Answer:

The main scale provides the primary measurement in millimeters or centimeters, depending on the caliper, and is used in conjunction with the Vernier scale for more accurate readings.