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प्रश्न
You are given a thread and a metre scale. How will you estimate the diameter of the thread?
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उत्तर
The diametre of a thread is so small that it cannot be measured using a metre scale.Wrap the thread on a uniform smooth rod in such a way that the coils thus formed are very close to each other. Measure the length of the thread using a metre scale. The diameter of the thread is given by the relation,
Diameter = `"Length of thread"/"Number of turns"`
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संबंधित प्रश्न
How many significant figures are present in the 208?
Round up the following upto three significant figures:
0.04597
How many significant figures should be present in the answer of the following calculation:-
`(0.02856 xx 298.15 xx 0.112)/0.5785`
How many significant figures should be present in the answer of the following calculation?
5 × 5.364
How many significant figures should be present in the answer of the following calculation?
0.0125 + 0.7864 + 0.0215
The mean diameter of a thin brass rod is to be measured by vernier callipers. Why is a set of 100 measurements of the diameter expected to yield a more reliable estimate than a set of 5 measurements only?
The mass of a box measured by a grocer’s balance is 2.300 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. What is
- What is the total mass of the box?
- What is the difference in the masses of the pieces to correct significant figures?
Precise measurements of physical quantities are a need of science. For example, to ascertain the speed of an aircraft, one must have an accurate method to find its positions at closely separated instants of time. This was the actual motivation behind the discovery of radar in World War II. Think of different examples in modern science where precise measurements of length, time, mass etc. are needed. Also, wherever you can, give a quantitative idea of the precision needed.
A LASER is a source of very intense, monochromatic, and unidirectional beam of light. These properties of a laser light can be exploited to measure long distances. The distance of the Moon from the Earth has been already determined very precisely using a laser as a source of light. A laser light beamed at the Moon takes 2.56 s to return after reflection at the Moon’s surface. How much is the radius of the lunar orbit around the Earth?
A SONAR (sound navigation and ranging) uses ultrasonic waves to detect and locate objects under water. In a submarine equipped with a SONAR the time delay between generation of a probe wave and the reception of its echo after reflection from an enemy submarine is found to be 77.0 s. What is the distance of the enemy submarine? (Speed of sound in water = 1450 m s–1).
State the number of significant figures in the following:
0.2370 g cm–3
Solve the numerical example.
A large ball 2 m in radius is made up of a rope of square cross-section with edge length 4 mm. Neglecting the air gaps in the ball, what is the total length of the rope to the nearest order of magnitude?
Which of the following has the highest number of significant figures?
The radius of the circle is 3.12 m. Calculate the area of the circle with regard to significant figures.
Write the rules for determining significant figures.
If the density of a solution is 3.12 g mL–1, the mass of 1.5 mL solution in significant figures is ______.
The numbers 2.745 and 2.735 on rounding off to 3 significant figures will give ______.
Which of the following measurements contains exactly two significant figures?
The radius of Earth is written as 0.64 × 10⁷ m in scientific notation. What is its order of magnitude?
