Question 9
The diagram shows an electric field pattern caused by two
positive and two negative point charges of equal magnitude placed at the four
corners of a square.
In which
direction does the force act on an electron at point X?
Reference: Past Exam Paper – November 2016 Paper 11 & 13 Q31
Solution:
Answer:
B.
The direction of the
electric field is from positive to negative.
The electric field lines
at any point show the direction of the force on a positive test charge. Since
we are dealing with an electron (which is has a negative charge), the direction
of the force on it would be opposite to the direction of the force on a
positive charge (which is indicated by the direction of the field).
But when the field lines
are curved, the direction of the force is along the tangent at that point. [A
and C are incorrect] The tangent is parallel to the field lines.
D shows the direction of
the force on a positive charge as this is in the same direction as the field at
that point.
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