A spherometer is an instrument used for the precise measurement of the radius of curvature of a sphere or a curved surface.

How do we measure the radius of the earth?

Compute the radius of the earth using the formula C (circumference) = 2 x pi x r (radius). Erastosthenes’ formula would look like this: 39,350 = 2 x 3.14 x r, or 6,267 kilometers.

How did scientists calculate radius and mass of Earth?

Because we know the radius of the Earth, we can use the Law of Universal Gravitation to calculate the mass of the Earth in terms of the gravitational force on an object (its weight) at the Earth’s surface, using the radius of the Earth as the distance.

What is the instrument used to measure earth?

gravimeter, also called gravity meter, sensitive device for measuring variations in the Earth’s gravitational field, useful in prospecting for oil and minerals.

How do you find the radius of a planet in physics?

Compute the radius of the earth using the formula C (circumference) = 2× pi×r (radius). Erastosthenes’ formula would look like this: 39,350= 2×3.14×r, or 6,267 kilometers. ‘

How does an earth ground tester work?

Working of Earth Tester : The two auxiliary electrodes P (potential electrode) and C (current electrode) are connected to the terminals P2 and C2 respectively. … When the generator is driven at its rated speed, the pointer of the moving coil instrument deflects and the earth tester indicates the resistance of the earth.

What is the radius of Earth in physics?

Earth radiusMetric system6,357 to 6,378 kmEnglish units3,950 to 3,963 mi

What is meant by earth resistance tester?

Definition: The instrument used for measuring the resistance of the earth is known as earth tester. All the equipment of the power system is connected to the earth through the earth electrode. The earth protects the equipment and personnel from the fault current.

What is the name of the instrument used for electrical insulation measurements?

Ohmmeter is a portable instrument which is used to measure the insulation resistance of the electrical machinery or system. It can be battery operated or mechanically operated (hand crank dc generator) and gives a direct reading in ohms. For this reason, it is also called as ohm meter.

How was the radius of the Earth first measured?

In the 2nd century B.C., a Greek philosopher named Eratosthenesis devised a simple geometric method to measure the radius of the Earth. He estimated the radius of the Earth by looking at two shadows at two different locations on the Earth. He choose two cities in Egypt – Alexandria in the North, and Aswan in the South.

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How do you measure the gravity of a planet?

PlanetVenusRadius (m)6.073 x 106Mass (kg)4.88 x1024g (m/s2)8.83

How do we measure the mass of a planet?

Answer 3: Yes. The masses of the planets are calculated most accurately from Newton’s law of gravity, a = (G*M)/(r2), which can be used to calculate how much gravitational acceleration (a) a planet of mass M will produce on objects at distance r away. One can solve for M once the other numbers are known.

How do you measure radius tool?

A radius gauge, also known as a fillet gauge, is a tool used to measure the radius of an object. Radius gauges require a bright light behind the object to be measured. The gauge is placed against the edge to be checked and any light leakage between the blade and edge indicates a mismatch that requires correction.

What is radius measured in physics?

The radius of a circle is the straight-line distance from the very center of the circle to any point on the circle.

How do you find the radius of a habitable zone?

The standard definition is that the habitable zone is the range of distances from a star in which liquid water could exist. To understand this we need to take a quick side trip into how one estimates temperature. because the area of a sphere of radius r is A = 4πr2 and the flux is the luminosity divided by the area.

What is the radius of the earth in meters in scientific notation?

Discovered ByKnown by the AncientsOrbit Eccentricity0.01671123Orbit Inclination0.00005 degreesEquatorial Inclination to Orbit23.4393 degreesMean RadiusMetric: 6,371.00 km English: 3,958.8 miles Scientific Notation: 6.3710 x 103 km

How do you find radius given gravity?

g = GM/r2, Where M is the mass of the Earth, r the radius of the Earth (or distance between the center of the Earth and you, standing on its surface), and G is the gravitational constant. G (without the subscripts) is the gravitational constant, and c is the speed of light.

What is the radius of Earth Class 11?

The radius of the earth is 6370 km and of mass is 3400 km if an object of 2000N on earth what will be the weight on mars the mass of mars is 0.11 on earthearth. At what distance above the surface of earth, the gravitational force will be reduced by 10%, if the radius of earth is 6370 Km.

What is the radius of the core of the earth?

The inner core has a radius of 1 216 km and the total radius of the core is 3486 km.

How do you measure earthing of equipment?

Insert the Negative wire in the Earthing of the Socket (Top single Hole). The Bulb must Glow with Full Brightness as before. If the Bulb does NOT Glow at all then there is NO Earthing / Grounding. If the Bulb Glows Dim, then it means the Earthing is Not Proper.

What is earth ground testing?

Electrical circuits have a separate ground, or ‘earth’, circuit that provides an alternate low-impedance path for electricity to safely reach the ground, in case of accidental physical contact. Ground testing is used to measure the performance of this circuit and check if it meets requirements.

What does a Megger do?

The Megger insulation tester is a small, portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. For good insulation, the resistance usually reads in the megohm range.

Which of the following instruments is best used for testing of insulation resistance?

The insulation resistance test, a.k.a., the “Megger test”, is as relevant as ever and, in many applications, is preferred to other insulation test methods. On the other hand, a megohmeter, also known as Megger, is often used to measure the insulation resistance of an insulated body.

What equipment is needed for insulation resistance?

The insulation resistance is measured by the equipment known as megger, which is a high resistance meter with a test voltage of about 500 volts dc.

What is megger ohm meter?

The megohmmeter (or megger) is an instrument for measuring very high resistances, such as the insulation resistance of electrical cables. … Thus, the megger is essentially an ohmmeter with a sensitive deflection instrument and a high voltage source.

How do you test earthing by Earth?

1. Press START and read out the resistance value. …
2. Record the reading on the Field Sheet at the appropriate location. …
3. The Earthing Tester has basically Constant Current generator which injects current into the earth between the two current terminals C1 (E) and C2 (H).

How can use the earth tester to measure earth resistance of earthing?

Earth resistivity is usually measured using the Wenner method, which involves the use of four temporary earth spikes. The spikes do not need to be moved as part of the testing procedure however – their location and spacing is determined by the depth at which it is required to determine the earth resistivity.

How many types of earth testers are there?

S.NOTypes of Testers1.Clamp-on Ammeter2Leakage Current Clamp-On Meters3.ESD Meters (Electrostatic Discharge Meter)4.Three Terminal Ground Resistance Meters

Why did Eratosthenes measure the earth?

Eratosthenes erected a pole in Alexandria, and on the summer solstice he observed that it cast a shadow, proving that the Sun was not directly overhead but slightly south. Recognizing the curvature of the Earth and knowing the distance between the two cities enabled Eratosthenes to calculate the planet’s circumference.

Who named Planet Earth?

All of the planets, except for Earth, were named after Greek and Roman gods and godesses. The name Earth is an English/German name which simply means the ground. It comes from the Old English words ‘eor(th)e’ and ‘ertha’. In German it is ‘erde’.

Who discovered Earth?

DiscoveryMass5 ± 2 M EarthSurface gravity1.9 +1.5 −1.0 (est.) gTemperatureTeq: 265 K (−8 °C; 17 °F)