How many electrons would transfer 1 J of energy to a screen?

[CivilSigma]

An elecetron has a mass of 9.11 * 10^-31 kg. If it moves across a television picture tube at a speed of 5.0 * 10^5 m/s. Calculate:
a) it's kinetic energy
b)how many such electrons would transfer 1 J of energy to the screen.

My answer to a) is 1.14 * 10^-19 J, which is correct.
My answer to b) is 1.14 * 10^19, which is not correct. The correct answer is 8.8 * 10^18. How did they get that? because if 1 electron has 1.14 * 10^-19 J then won't we need 1.14 * 10^19 electrons for 1 J ?

 

[gneill]

My answer to a) is 1.14 * 10^-19 J, which is correct.
My answer to b) is 1.14 * 10^19, which is not correct. The correct answer is 8.8 * 10^18. How did they get that? because if 1 electron has 1.14 * 10^-19 J then won't we need 1.14 * 10^19 electrons for 1 J ?

Changing the sign of the exponent is not the same as division... What about the mantissa of the number?

 

[CivilSigma]

om >.< I know what i did wrong! Stupid mistake. Thanks for that comment.