Question

An alpha particle is accelerated from rest through a potential difference of 100 V.its final kinetic energy is ...
1. 100eV
2. 1000eV
3. 200eV
4. 400eV

Answer 1

Answer ⇒ Option (c). 200 eV.

Explanation ⇒ We know that the charge on alpha particle is 2e, but let 2e = q.

Now,

Since, particle is initially at rest, thus,

Initial velocity (u) = 0

Let final velocity = v.

Let the distance covered by the alpha particle of mass m in an region of electric field of strength E be x.

Then, Using the equation of motion,

v² - u² = 2aS

∴ v² - 0² = 2qE/m × x

∴ 1/2 × mv² = qEx

∴ K.E. = qV   [∵ EX = V.]

Now, q = 2e and V = 100 V.

∴ K.E. =  2e × 100

∴ K.E. = 200e V.

∴ K.E. = 200 eV.

Hence, the kinetic energy of the alpha particle is 200 eV.

∴ Option (c). is correct.

Hope it helps.

Answer 2

Answer:

Explanation:

C