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An electron (mass = 9xx10^(-31)kg, charg...

An electron (mass = `9xx10^(-31)`kg, charge = `1.6xx10^(-19)C`) whose kinetic energy is `7.2xx10^(-18)`joule is moving in a circular orbit in a magnetic field of `9xx10^(-5)Wb//m^(2)`. The radius of the orbit is _____ .

A

1.25 cm

B

2.5 cm

C

12.5 cm

D

25.0 cm

Text Solution

Verified by Experts

The correct Answer is:
D
`E=7.2xx10^(-18)J`
`q=1.6xx10^(-19)C`
`m=9xx10^(-31)kg`
`B=9xx10^(-5)Wb//m^(2)`
Radius of circular path `r=sqrt(2mE)/(qB)`
`thereforer=sqrt((2xx9xx10^(-31)xx7.2xx10^(-18))/(1.6xx10^(-19)xx9xx10^(-15)))`
= 0.25 m = 25 cm
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