An electron of mass 9.1 x 10^-31 kg revolves in a circle of radius 0.529 Å around the nucleus with speed of 2.2x10⁶ m/s. Show that its angular momentum is equal to h/2 π, where h is Planck's constant.

Solution

Mass of the electron = 9.1 $cross times$ 10^-31 kg
Radius of the circle, r = 0.529 $straight A with 0 on top$
Speed = 2.2 x 10⁶ m/s
The angular momentum of electron is,
L = mvr
= 9.1 x 10^-31x 2.19 x 10⁶x 0.527 x 10^-10
= 1.0502 x 10^-34J s
$Also space space space straight h space equals space fraction numerator straight h over denominator 2 straight pi end fraction equals fraction numerator 6.6 cross times 10 to the power of negative 34 end exponent over denominator 2 cross times 3.142 end fraction equals 1.0502 cross times 10 to the power of negative 34 end exponent space Js$
Thus, L = $fraction numerator straight h over denominator 2 straight pi end fraction$

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Units And Measurement

An electron of mass 9.1 x 10^-31 kg revolves in a circle of radius 0.529 Å around the nucleus with speed of 2.2x10⁶ m/s. Show that its angular momentum is equal to h/2 π, where h is Planck's constant.

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Is one unit sufficient to measure a physical quantity?

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How many fundamental quantities are there in Physics?

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Units And Measurement

An electron of mass 9.1 x 10-31 kg revolves in a circle of radius 0.529 Å around the nucleus with speed of 2.2x106 m/s. Show that its angular momentum is equal to h/2 π, where h is Planck's constant.

Some More Questions From Units and Measurement Chapter

Can we use different units to measure same physical quantity?

To measure a physical quantity X, the unit U is repeatedly used for n times. What is the magnitude of physical quantity?

Does the numerical factor in the quantitative measurement depend on the system of unit used?

Is one unit sufficient to measure a physical quantity?

Can a physical quantity have two or more units? Give example.

What are fundamental quantities?

How many fundamental quantities are there in mechanics?

How many fundamental quantities are there in Physics?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

An electron of mass 9.1 x 10^-31 kg revolves in a circle of radius 0.529 Å around the nucleus with speed of 2.2x10⁶ m/s. Show that its angular momentum is equal to h/2 π, where h is Planck's constant.