Question

An electron is continuously accelerated in a vacuum tube by the application of a potential difference.if it's de Broglie wavelength decreases by 1% over a path length of L cm,then it's kinetic energy
1) increases by 1%
2)increases by 2%
3) decreases by 2%
4) decreases by 0.5%
plzz show me how to solve step by step working​

Answer 1

Answer:

We know that, λ=

2mkE

h

⇒λ∝

kE

1

.........(1)

Let λ

1

=λ,KE

1

=E.........(1)

∴ according to question, λ

2

=0.9λ..........(2)

( λ is decreased by 10%)

KE

2

=?

⇒KE

2

=

λ

2

2

λ

1

2

×KE

1

=

(0.9λ)

2

λ

2

×E

=

81

100E

[Putting values from eq.(1) and (2)]

∴% increase =

KE

1

KE

2

−KE

1

×100

=

E

81

100

E−E

×100

=

81

19

×100

=23.4%

∴ The kinetic energy increases by 23.4%

Explanation:

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