Question 15
A charged particle is
moving in a uniform electric field.
For the motion of the
particle due to the field, which quantity has a constant non-zero value?
A acceleration
B displacement
C rate
of change of acceleration
D velocity
Reference: Past Exam Paper – June 2016 Paper 11 Q28
Solution:
Answer:
A.
The charged particle
experiences a force when in the electric field.
Let electric field strength
= E (E is constant as the
electric field is uniform)
Charge of particle = q
The force on a particle of
charge q in a uniform electric field of field strength E is given by F = qE.
From Newton’s 2nd
law: F = ma
A resultant force causes
an acceleration a.
ma = qE
Acceleration a = qE / m for mass m
Therefore, the
acceleration of the particle is constant (since q, E and m are all constants) and
non-zero. [A is correct] If the acceleration was zero, there would be no force
on the particle (as F = ma).
The acceleration being
constant means that it is NOT changing. So,
Rate of change of
acceleration = 0 [C is incorrect]
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