# the value of universal gravitational constant g was first experimentally determined by

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## The value of universal gravitational constant 'G' was first experimentally determined by :

Click here👆to get an answer to your question ✍️ The value of universal gravitational constant 'G' was first experimentally determined by :

The value of universal gravitational constantQuestion ′ G ′

was first experimentally determined by :

**A**

## Galileo

**B**

## Newton

**C**

## Cavendish

**D**

## Kelvin

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Updated on : 2022-09-05

Solution Verified by Toppr

Correct option is C)

Cavendish experiment . The Cavendish experiment , performed in 1797–1798 by British scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate value for the gravitational constantHence,

option C is correct answer.

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## The value of gravitational constant G was first experimentally class 11 physics CBSE

The value of gravitational constant G was first experimentally determined by A Galileo B Newton C Cavendish D Kelvin

The value of gravitational constant G was first experimentally determined by:A) Galileo B) Newton C) Cavendish D) Kelvin Answer Verified 223.8k+ views 2 likes

**Hint:**The value of gravitational constant, G first determined was

6.75× 10 −11 N m 2 k g −2 6.75×10−11Nm2kg−2 .

**Complete step by step answer:**

After nearly a century in 1798, Lord Henry Cavendish came to determine the value for that constant G by the experiment of torsional balance.

He attached the two small lead spheres in each side of the rod and the rod was suspended by a thin wire. When the rod is twisted, the torsion of the wire begins to exert the torsional force which is proportional to the angle of rotation. Then the more twisting leads the system to restore itself backward more. By this, Cavendish calculated the relationship between the angle of rotation to the amount of torsional force.

And then he brought two large spheres near to the small lead spheres connected to the rod. The large spheres exert the gravitational force on the small spheres which causes the rod to twist. Once the torsional force equals the gravitational force, the twisting stops. The rod comes to rest. Using this, Cavendish calculated the force of attraction. Then finally he determined the value of G.

Cavendish determined G as

6.75× 10 −11 N m 2 k g −2 6.75×10−11Nm2kg−2

. Now the accepted value is

6.67× 10 −11 N m 2 k g −2 6.67×10−11Nm2kg−2 ∴ ∴

**The correct option is option (C).**

**Additional information:**

(i)Sir Issac Newton in 1687, in his book philosophiae Naturalis Principia Mathematica discovered the term Gravitational constant for the first time while explaining the gravitational force.

(ii)Newton states that the gravitational force between any two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.

∴ F grav α m 1 m 2 d 2 ∴Fgravαm1m2d2

. To remove this proportionality he introduced the constant G.

F grav =G m 1 m 2 d 2 Fgrav=Gm1m2d2

(iii) After nearly a century in 1798, Lord Henry Cavendish came to determine the value for that constant G by the experiment of torsional balance.

(vi) Cavendish determined G as

6.75× 10 −11 N m 2 k g −2 6.75×10−11Nm2kg−2

. Now the accepted value is

6.67× 10 −11 N m 2 k g −2 6.67×10−11Nm2kg−2 .

**Note:**

The gravitational force is the weakest of all forces in the universe. It has an appreciable value only if it is between the two objects having large masses.

## [Solved] The value of ‘G’, the Universal Gravitational Co

The correct answer is Cavendish. Key Points Cavendish experiment. The Cavendish experiment, performed in 1797–1798 by British scientist Hen

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## The value of ‘G’, the Universal Gravitational Constant, was measured experimentally by:

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Newton Cavendish Copernicus Kepler

## Answer (Detailed Solution Below)

Option 2 : Cavendish

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## Detailed Solution

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The correct answer is **Cavendish**.

**Key Points**

**Cavendish experiment.**

The Cavendish experiment, performed in 1797–1798 by British scientist **Henry Cavendish.**

It was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield an accurate value for the gravitational constant.

Cavendish was the first to establish the value of the universal gravitational constant G through his experiment.

The apparatus used by him included two small spheres made of lead attached to the ends of a bar of length L.

The bar is suspended from rigid support by a fine wire.

He noticed that, when two spheres were brought simultaneously on the opposite sides of the small spheres, the big spheres attract the nearby small ones by an equal and opposite gravitational force (F). This produced torque of magnitude FL.

Due to this torque, the suspended wire gets twisted until the restoring torque of the wire equals the gravitational torque.

If θ was the angle of twist of the wire, the restoring torque = τθ (Where τ is the restoring couple per unit angle of twist)

On equating the equations,

FL = τθ θ ⇒GMmd2L=τθ

Where m is the mass of the small sphere, and M is the mass of the big sphere.

Observation of θ thus enables one to calculate G from this equation.

**Additional Information**

The Cavendish experiment determines the magnitude of gravitational attraction between two bodies.

It is based on the principle that a suspended wire resists torsion with a force that is due to gravity.

Hence, it is based on force-torque equilibrium.

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