Question

An alpha particle kept in an electric field of strength $100N{{C}^{-1}}$will experience a force of:
A: $3.2\times {{10}^{-17}}N$
B: $1.6\times {{10}^{-6}}N$
C: $3.2\times {{10}^{15}}N$
D: $1.6\times {{10}^{15}}N$

Answer 1

Hint: We’re given an alpha particle whose charge is a known value to us. We’re also given the electric field. We can easily find the force experienced by direct substitution into the formula.

Complete Step by step answer:
As we know, $F=q\times E$, where F is the force experienced by the particle, E is the electric field and q is the charge possessed by the particle in the given field.
An electric field is capable of exerting a force on particles inside an electric field. The same instance is given here. We’re given an alpha particle whose charge can be given by
$q=+2e=2\times 1.6\times {{10}^{-19}}=3.2\times {{10}^{-19}}C$
We’re also given the electric field in which the alpha particle resides, that is
$E=100N{{C}^{-1}}$
We know that the alpha particle in this field will experience a force $F=q\times E$
Hence, on substituting the values. We obtain
$\
  F=3.2\times {{10}^{-19}}\times 100 \\
 \Rightarrow F=3.2\times {{10}^{-17}}N \\
$
Therefore we can conclude that the particle experiences a force of $3.2\times {{10}^{-17}}N$

Hence, option A is the correct answer among the given options.

Note: It should be noted that the direction of the electric field is the direction of that force on a positive charge. The actual force on a particle with charge q is given by F = qE. It points in the opposite direction of the electric field E for a negative charge.