Question

An electron of mass 9 x 10-31 kg moves with a

speed of 107

m/s. It acquires a K.E. of

1) 562.50 eV 2) 1125 eV

3) 1250 eV 4) 281.25 eV​

Answer 1

Explanation:

K.E. =>

2

1

mv

2

=>

2

1

×9×10

−31

×(10

7

)

2

=> 4.5×10

−17

J (∵1.6×10

−19

eV=1J)

=>

1.6×10

−19

4.5×10

−17

eV

=> 2.8125×10

2

eV

=>281.25 eV.